Self-stopping polishing composition and method for bulk oxide planarization

ABSTRACT

The invention provides a chemical-mechanical polishing composition comprising an abrasive, a self-stopping agent, an aqueous carrier, and a cationic polymer. This invention additionally provides a method suitable for polishing a dielectric substrate.

BACKGROUND OF THE INVENTION

In the fabrication of integrated circuits and other electronic devices,multiple layers of conducting, semiconducting, and dielectric materialsare deposited onto or removed from a substrate surface. As layers ofmaterials are sequentially deposited onto and removed from thesubstrate, the uppermost surface of the substrate may become non-planarand require planarization. Planarizing a surface, or “polishing” asurface, is a process where material is removed from the surface of thesubstrate to form a generally even, planar surface. Planarization isuseful in removing undesired surface topography and surface defects,such as rough surfaces, agglomerated materials, crystal lattice damage,scratches, and contaminated layers or materials. Planarization also isuseful in forming features on a substrate by removing excess depositedmaterial used to fill the features and to provide an even surface forsubsequent levels of metallization and processing.

Compositions and methods for planarizing or polishing the surface of asubstrate are well known in the art. Chemical-mechanical planarization,or chemical-mechanical polishing (CMP), is a common technique used toplanarize substrates. CMP utilizes a chemical composition, known as aCMP composition or more simply as a polishing composition (also referredto as a polishing slurry), for selective removal of material from thesubstrate. Polishing compositions typically are applied to a substrateby contacting the surface of the substrate with a polishing pad (e.g.,polishing cloth or polishing disk) saturated with the polishingcomposition. The polishing of the substrate typically is further aidedby the chemical activity of the polishing composition and/or themechanical activity of an abrasive suspended in the polishingcomposition or incorporated into the polishing pad (e.g., fixed abrasivepolishing pad).

As the size of integrated circuits is reduced and the number ofintegrated circuits on a chip increases, the components that make up thecircuits must be positioned closer together in order to comply with thelimited space available on a typical chip. Effective isolation betweencircuits is important for ensuring optimum semiconductor performance. Tothat end, shallow trenches are etched into the semiconductor substrateand filled with insulating material to isolate active regions of theintegrated circuit. More specifically, shallow trench isolation (STI) isa process in which a silicon nitride layer is formed on a siliconsubstrate, shallow trenches are formed via etching or photolithography,and a dielectric layer is deposited to fill the trenches. Due tovariation in the depth of trenches formed in this manner, it istypically necessary to deposit an excess of dielectric material on topof the substrate to ensure complete filling of all trenches. Thedielectric material (e.g., a silicon oxide) conforms to the underlyingtopography of the substrate.

Thus, after the dielectric material has been placed, the surface of thedeposited dielectric material is characterized by an uneven combinationof raised areas of the dielectric material separated by trenches in thedielectric material, the raised areas and trenches of the dielectricmaterial aligning with corresponding raised areas and trenches of theunderlying surface. The region of the substrate surface that includesthe raised dielectric material and trenches is referred to as a patternfield of the substrate, e.g., as “pattern material,” “pattern oxide,” or“pattern dielectric.” The pattern field is characterized by a “stepheight,” which is the difference in height of the raised areas of thedielectric material relative to the trench height.

The excess dielectric material is typically removed by a CMP process,which additionally provides a planar surface for further processing.During removal of the raised area material, an amount of material fromthe trenches also will be removed. This removal of material from thetrenches is referred to as “trench erosion” or “trench loss.” Trenchloss is the amount (thickness, e.g., in Angstroms (Å)) of materialremoved from trenches in achieving planarization of pattern dielectricmaterial by eliminating an initial step height. Trench loss iscalculated as the initial trench thickness minus a final trenchthickness. Desirably, the rate of removal of material from trenches iswell below the rate of removal from raised areas. Thus, as material ofthe raised areas is removed (at a faster rate compared to material beingremoved from the trenches) the pattern dielectric becomes a highlyplanarized surface that may be referred to as a “blanket” region of theprocessed substrate surface, e.g., “blanket dielectric” or “blanketoxide.”

A polishing composition can be characterized according to its polishingrate (i.e., removal rate) and its planarization efficiency. Thepolishing rate refers to the rate of removal of a material from thesurface of the substrate and is usually expressed in terms of units oflength (thickness, e.g., in Angstroms (Å)) per unit of time (e.g., perminute). Different removal rates relating to different regions of asubstrate, or to different stages of a polishing step, can be importantin assessing process performance. A “pattern removal rate” is the rateof removal of dielectric material from raised areas of patterndielectric layer at a stage of a process during which a substrateexhibits a substantial step height. “Blanket removal rate” refers to arate of removal of dielectric material from planarized (i.e., “blanket”)areas of a pattern dielectric layer at an end of a polishing step, whenstep height has been significantly (e.g., essentially entirely) reduced.Planarization efficiency relates to step height reduction versus amountof material removed from the substrate (i.e., step height reductiondivided by trench loss). Specifically, a polishing surface, e.g., apolishing pad, first contacts the “high points” of the surface and mustremove material in order to form a planar surface. A process thatresults in achieving a planar surface with less removal of material isconsidered to be more efficient than a process requiring removal of morematerial to achieve planarity.

Often the rate of removal of the silicon oxide pattern material can berate-limiting for the dielectric polishing step in STI processes, andtherefore high removal rates of the silicon oxide pattern are desired toincrease device throughput. However, if the blanket removal rate is toorapid, overpolishing of oxide in exposed trenches results in trencherosion and increased device defectivity. Overpolishing and associatedtrench loss can be avoided if the blanket removal rate is lowered.

It is desirable in certain polishing applications for a CMP compositionto exhibit “self-stopping” behavior such that when a large percentage ofthe “high points” of the surface (i.e., raised areas) have been removed,the removal rate decreases. In self-stopping polishing applications, theremoval rate is effectively high while a significant step height ispresent at the substrate surface and then the removal rate is lowered asthe surface becomes effectively planar. In various dielectric polishingsteps (e.g., of an STI process) the rate of removal of patterndielectric material (e.g., dielectric layer) is typically arate-limiting factor of the overall process. Therefore, high removalrates of pattern dielectric material are desired to increase throughput.Good efficiency in the form of relatively low trench loss is alsodesirable. Further, if the removal rate of dielectric remains high afterachieving planarization, overpolishing occurs, resulting in added trenchloss.

Advantages of self-stopping slurries result from the reduced blanketremoval rate, which produces a wide endpoint window. For example,self-stopping behavior allows for polishing of substrates having reduceddielectric film thickness, allowing for a reduced amount of material tobe deposited over a structured lower layer. Also, motor torque endpointdetection can be used for more effective monitoring of final topography.Substrates can be polished with lower trench loss by avoidingoverpolishing or unnecessary removal of dielectric after planarization.

Self-stopping CMP compositions currently have been developed based onceria/anionic polyelectrolyte systems. For example, U.S. PatentApplication Publication 2008/0121839 discloses a polishing compositioncomprising inorganic abrasives, polyacrylic acid/maleic acid copolymer,and gemini surfactant. Korean Patent No. 10-1524624 discloses apolishing composition comprising ceria, a carboxylic acid, and mixedamine compounds (English-language abstract). International PatentApplication Publication No. WO 2006/115393 discloses a polishingcomposition comprising ceria, a hydroxycarboxylic acid, and an aminoalcohol. However, as the structure of semiconductor devices becomes morecomplicated and especially as NAND technology is moved from 2D to 3D,current self-stopping CMP compositions, due to the use of anionicpolymer, are being challenged by the limited step height reduction ratebrought about by electrostatic repulsion between the abrasive and thesilicon oxide surface.

A need remains for compositions and methods for chemical-mechanicalpolishing of silicon oxide-containing substrates that will provideuseful removal rates while also providing improved planarizationefficiency. The invention provides such polishing compositions andmethods. These and other advantages of the invention, as well asadditional inventive features, will be apparent from the description ofthe invention provided herein.

BRIEF SUMMARY OF THE INVENTION

The invention provides a chemical-mechanical polishing compositioncomprising an abrasive, a self-stopping agent, an aqueous carrier, andoptionally a cationic compound, as well as a method suitable forpolishing a substrate using the inventive polishing composition.

More specifically, the invention provides a chemical-mechanicalpolishing composition comprising (a) an abrasive, (b) a self-stoppingagent of the formula Q-B, wherein Q may be a substituted orunsubstituted hydrophobic group, or a group imparting a sterichindrance, B is a binding group, wherein the binding group has thestructure; C(O)—X—OH or —C(O)—OH, wherein X is a C1-C2 alkyl group, and(c) an aqueous carrier, wherein the polishing composition has a pH ofabout 3 to about 9.

The invention also provides a chemical-mechanical polishing compositioncomprising (a) an abrasive comprising ceria, (b) a self-stopping agentselected from kojic acid (5-Hydroxy-2-(hydroxymethyl)-4H-pyran-4-one),crotonic acid ((E)-2-butenoic acid), tiglic acid((2E)-2-Methylbut-2-enoic acid), valeric acid (pentanoic acid),2-pentenoic acid, maltol (3-Hydroxy-2-methyl-4H-pyran-4-one), benzoicacid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeicacid, ethyl maltol, potassium sorbate, sorbic acid, and combinationsthereof, and (c) an aqueous carrier, wherein the polishing compositionhas a pH of about 3 to about 9.

The invention also provides a chemical-mechanical polishing compositioncomprising (a) an abrasive comprising ceria, (b) a self-stopping agentselected from a compound of formula (I):

wherein R is selected from the group consisting of hydrogen, alkyl,cycloalkyl, aryl, heterocyclic alkyl, and heterocyclic aryl, each ofwhich may be substituted or unsubstituted; a compound of formula (II):

wherein each of X¹-X³ is independently selected from N, O, S, asp²-hybridized carbon, and CY¹Y², wherein each of Y¹ and Y² isindependently selected from hydrogen, hydroxyl, C₁-C₆ alkyl, halogen,and combinations thereof, and each of Z¹-Z³ is independently selectedfrom hydrogen, hydroxyl, C₁-C₆ alkyl, and combinations thereof, each ofwhich may be substituted or unsubstituted; a compound of formula (III):Z—(C(X¹X²)_(n))_(p)—CO₂M  (III),wherein Z is selected from C₁-C₆ alkyl, C₁-C₆ alkenyl, C₁-C₆ alkynyl,and aryl (e.g., phenyl, benzyl, naphthyl, azulene, anthracene, pyrene,etc.), X¹ and X² are independently selected from hydrogen, hydroxy,amino, and C₁-C₆ alkyl, and wherein X¹ and X² taken together with theattached carbon can form a sp²-hybridized carbon, n is 1 or 2, p is 0-4,and M is selected from hydrogen and a suitable counterion (e.g., a groupI metal), each of which may be substituted or unsubstituted; andcombinations thereof, a compound of formula (IV):

where X, Y, and Z are independently selected from H, O, S, NH, and CH₂,R¹, R² and R³ are independently selected from H, alkyl, alkenyl,alkynyl, aryl, halo, and haloalkyl, and M is selected from hydrogen anda suitable counterion, (c) optionally a cationic polymer and (d) anaqueous carrier, wherein the polishing composition has a pH of about 3to about 9.

The invention further provides a method of chemically-mechanicallypolishing a substrate comprising (i) providing a substrate, wherein thesubstrate comprises a pattern dielectric layer on a surface of thesubstrate, wherein the pattern dielectric layer comprises a raised areaof dielectric material (e.g., active area vs. peri area), and whereinthe initial step height of the pattern dielectric layer describes theoxide thickness range (e.g., active vs. peri), (iii) providing achemical-mechanical polishing composition as described herein, (iv)contacting the substrate with the polishing pad and thechemical-mechanical polishing composition, and (v) moving the polishingpad and the chemical-mechanical polishing composition relative to thesubstrate to abrade at least a portion of the pattern dielectric layeron a surface of the substrate to polish the substrate.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 (not to scale) illustrates a cross-sectional view of an examplesubstrate to illustrate active area, trench areas, step height, andtrench loss.

FIG. 2 illustrates the polishing performance of an inventive polishingcomposition as a function of pitch width and pattern density of asubstrate.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a chemical-mechanical polishing compositioncomprising (a) an abrasive, (b) a self-stopping agent of the formulaQ-B, wherein Q may be a substituted or unsubstituted hydrophobic group,or a group imparting a steric hindrance, B is a binding group, whereinthe binding group has the structure; C(O)—X—OH or —C(O)—OH, wherein X isa C1-C2 alkyl group, and (c) an aqueous carrier, wherein the polishingcomposition has a pH of about 3 to about 9.

The polishing composition of the invention comprises an abrasive. Theabrasive of the polishing composition desirably is suitable forpolishing a non-metal portion of the substrate (e.g., pattern dielectricmaterial, blanket dielectric material, pattern oxide material, blanketoxide material, etc.). Suitable abrasives include ceria (e.g., CeO₂),zirconia (e.g., ZrO₂), silica (e.g., SiO₂), and combinations thereof.

In a preferred embodiment, the abrasive is selected from ceria,zirconia, and combinations thereof. In another preferred embodiment, theabrasive is ceria.

Both ceria abrasives and zirconia abrasives are well known in the CMPart and are commercially available. Examples of suitable ceria abrasivesinclude wet-process ceria, calcined ceria, and metal-doped ceria, amongothers. Examples of suitable zirconia abrasives include metal-dopedzirconia and non-metal-doped zirconia, among others. Among metal dopedzirconia are cerium-, calcium-, magnesium-, or yttrium-doped zirconiawith dopant element weight percentage preferentially in a range from0.1-25%.

Ceria abrasives suitable for use in the inventive polishingcompositions, and processes for their preparation, are described in U.S.patent application Ser. No. 14/639,564, filed Mar. 5, 2015, entitled“Polishing Composition Containing Ceria Abrasive,” now U.S. Pat. No.9,505,952, and U.S. patent application Ser. No. 15/207,973, filed Jul.12, 2016, entitled “Methods and Compositions for Processing DielectricSubstrate,” published as U.S. Patent Application Publication No.2017/0014969, the disclosures of which are incorporated by referenceherein.

A preferred abrasive is wet-process ceria particles. The polishingcomposition can comprise a single type of abrasive particles or multipledifferent types of abrasive particles, based on size, composition,method of preparation, particle size distribution, or other mechanicalor physical properties. Ceria abrasive particles can be made by avariety of different processes. For example, ceria abrasive particlescan be precipitated ceria particles or condensation-polymerized ceriaparticles, including colloidal ceria particles.

The ceria abrasive particles can be made by any suitable process. As anexample, the ceria abrasive particles can be wet-process ceria particlesmade according to the following process. Typically, the first step insynthesizing wet-process ceria particles is to dissolve a ceriaprecursor in water. The ceria precursor can be any suitable ceriaprecursor, and can include a ceria salt having any suitable charge,e.g., Ce³⁺ or Ce⁴⁺. Suitable ceria precursors include, for example,cerium III nitrate, cerium IV ammonium nitrate, cerium III carbonate,cerium IV sulfate, and cerium III chloride. Preferably, the ceriaprecursor is cerium III nitrate.

The pH of the ceria precursor solution typically is increased to formamorphous Ce(OH)₃. The pH of the solution can be increased to anysuitable pH. For example, the pH of the solution can be increased to apH of about 10 or more, e.g., a pH of about 10.5 or more, a pH of about11 or more, or a pH of about 12 or more. Typically, the solution willhave a pH of about 14 or less, e.g., a pH of about 13.5 or less, or a pHof about 13 or less. Any suitable base can be used to increase the pH ofthe solution. Suitable bases include, for example, KOH, NaOH, NH₄OH, andtetramethylammonium hydroxide. Organic bases such as, for example,ethanolamine and diethanolamine, also are suitable. The solution willbecome white and cloudy as the pH increases and amorphous Ce(OH)₃ isformed.

The ceria precursor solution typically is mixed for several hours. Forexample, the solution can be mixed for about 1 hour or more, e.g., about2 hours or more, about 4 hours or more, about 6 hours or more, about 8hours or more, about 12 hours or more, about 16 hours or more, about 20hours or more, or about 24 hours or more. Typically, the solution ismixed for about 1 hour to about 24 hours, e.g., about 2 hours, about 8hours, or about 12 hours. When mixing is complete, the solution can betransferred to a pressurized vessel and heated.

The ceria precursor solution can be heated to any suitable temperature.For example, the solution can be heated to a temperature of about 50° C.or more, e.g., about 75° C. or more, about 100° C. or more, about 125°C. or more, about 150° C. or more, about 175° C. or more, or about 200°C. or more. Alternatively, or in addition, the solution can be heated toa temperature of about 500° C. or less, e.g., about 450° C. or less,about 400° C. or less, about 375° C. or less, about 350° C. or less,about 300° C. or less, about 250° C. or less, about 225° C., or about200° C. or less. Thus, the solution can be heated to a temperaturewithin a range bounded by any two of the aforementioned endpoints. Forexample, the solution can be heated to a temperature of about 50° C. toabout 300° C., e.g., about 50° C. to about 275° C., about 50° C. toabout 250° C., about 50° C. to about 200° C., about 75° C. to about 300°C., about 75° C. to about 250° C., about 75° C. to about 200° C., about100° C. to about 300° C., about 100° C. to about 250° C., or about 100°C. to about 225° C.

The ceria precursor solution typically is heated for several hours. Forexample, the solution can be heated for about 1 hour or more, e.g.,about 5 hours or more, about 10 hours or more, about 25 hours or more,about 50 hours or more, about 75 hours or more, about 100 hours or more,or about 110 hours or more. Alternatively, or in addition, the solutioncan be heated for about 200 hours or less, e.g., about 180 hours orless, about 165 hours or less, about 150 hours or less, about 125 hoursor less, about 115 hours or less, or about 100 hours or less. Thus, thesolution can be heated for a time period bounded by any two of theaforementioned endpoints. For example, the solution can be heated forabout 1 hour to about 150 hours, e.g., about 5 hours to about 130 hours,about 10 hours to about 120 hours, about 15 hours to about 115 hours, orabout 25 hours to about 100 hours.

After heating, the ceria precursor solution can be filtered to separatethe precipitated ceria particles. The precipitant can be rinsed withexcess water to remove unreacted ceria precursor. The mixture ofprecipitant and excess water can be filtered following each rinse stepto remove impurities. Once adequately rinsed, the ceria particles can bedried for additional processing, e.g., sintering, or the ceria particlescan be directly redispersed.

The ceria particles optionally can be dried and sintered prior toredispersion. The terms “sintering” and “calcining” are usedinterchangeably herein to refer to the heating of the ceria particlesunder the conditions described below. Sintering the ceria particlesimpacts their resulting crystallinity. Without wishing to be bound byany particular theory, it is believed that sintering the ceria particlesat high temperatures and for extended periods of time reduces defects inthe crystal lattice structure of the particles. Any suitable method canbe used to sinter the ceria particles. As an example, the ceriaparticles can be dried, and then can be sintered at an elevatedtemperature. Drying can be carried out at room temperature, or at anelevated temperature. In particular, drying can be carried out at atemperature of about 20° C. to about 40° C., e.g., about 25° C., about30° C., or about 35° C. Alternatively, or in addition, drying can becarried out at an elevated temperature of about 80° C. to about 150° C.,e.g., about 85° C., about 100° C., about 115° C., about 125° C., orabout 140° C. After the ceria particles have been dried, they can beground to create a powder. Grinding can be carried out using anysuitable grinding material, such as zirconia.

The ceria particles can be sintered in any suitable oven, and at anysuitable temperature. For example, the ceria particles can be sinteredat a temperature of about 200° C. or more, e.g., about 215° C. or more,about 225° C. or more, about 250° C. or more, about 275° C. or more,about 300° C. or more, about 350° C. or more, or about 375° C. or more.Alternatively, or in addition, the ceria particles can be sintered at atemperature of about 1000° C. or less, e.g., about 900° C. or less,about 750° C. or less, about 650° C. or less, about 550° C. or less,about 500° C. or less, about 450° C. or less, or about 400° C. or less.Thus, the ceria particles can be sintered at a temperature bounded byany two of the aforementioned endpoints. For example, the ceriaparticles can be sintered at a temperature of about 200° C. to about1000° C., e.g., about 250° C. to about 800° C., about 300° C. to about700° C., about 325° C. to about 650° C., about 350° C. to about 600° C.,about 350° C. to about 550° C., about 400° C. to about 550° C., about450° C. to about 800° C., about 500° C. to about 1000° C., or about 500°C. to about 800° C.

The ceria particles can be sintered for any suitable length of time. Forexample, the ceria particles can be sintered for about 1 hour or more,e.g., about 2 hours or more, about 5 hours or more, or about 8 hours ormore. Alternatively, or in addition, the ceria particles can be sinteredfor about 20 hours or less, e.g., about 18 hours or less, about 15 hoursor less, about 12 hours or less, or about 10 hours or less. Thus, theceria particles can be sintered for a time period bounded by any two ofthe aforementioned endpoints. For example, the ceria particles can besintered for about 1 hour to about 20 hours, e.g., about 1 hour to about15 hours, about 1 hour to about 10 hours, about 1 hour to about 5 hours,about 5 hours to about 20 hours, or about 10 hours to about 20 hours.

The ceria particles also can be sintered at various temperatures and forvarious lengths of time within the ranges described above. For example,the ceria particles can be sintered in a zone furnace, which exposes theceria particles to one or more temperatures for various lengths of time.As an example, the ceria particles can be sintered at a temperature ofabout 200° C. to about 1000° C. for about 1 hour or more, and then canbe sintered at a different temperature that is within the range of about200° C. to about 1000° C. for about 1 hour or more.

The ceria particles typically are redispersed in a suitable carrier,e.g., an aqueous carrier, particularly water. If the ceria particles aresintered, then the ceria particles are redispersed after the completionof sintering. Any suitable process can be used to redisperse the ceriaparticles. Typically, the ceria particles are redispersed by loweringthe pH of a mixture of the ceria particles and water using a suitableacid. As the pH is lowered, the surface of the ceria particles developsa cationic zeta potential. This cationic zeta potential createsrepulsion forces between the ceria particles, which facilitates theirredispersion. Any suitable acid can be used to lower the pH of themixture. Suitable acids include, for example hydrochloric acid andnitric acid. Organic acids which are highly water-soluble and havehydrophilic functional groups also are suitable. Suitable organic acidsinclude, for example, acetic acid. Acids with multivalent anions, suchas H₃PO₄ and H₂SO₄, generally are not preferred. The pH of the mixturecan be lowered to any suitable pH. For example, the pH of the mixturecan be lowered to about 2 to about 5, e.g., about 2.5, about 3, about3.5, about 4, or about 4.5. Typically, the pH of the mixture is notlowered to less than about 2.

The redispersed ceria particles typically are milled to reduce theirparticle size. Preferably, the ceria particles are milled simultaneouslywith redispersion. Milling can be carried out using any suitable millingmaterial, such as zirconia. Milling also can be carried out usingsonication or wet-jet procedures. After milling, the ceria particles canbe filtered to remove any remaining large particles. For example, theceria particles can be filtered using a filter having a pore size ofabout 0.3 μm or more, e.g., about 0.4 μm or more, or about 0.5 μm ormore.

The abrasive particles (e.g., ceria abrasive particles) preferably havea median particle size of about 40 nm to about 100 nm. The particle sizeof a particle is the diameter of the smallest sphere that encompassesthe particle. The particle size of the abrasive particles can bemeasured using any suitable technique. For example, the particle size ofthe abrasive particles can be measured using a disc centrifuge, i.e., bydifferential centrifugal sedimentation (DCS). Suitable disc centrifugeparticle size measurement instruments are commercially available, suchas from CPS Instruments (Prairieville, La.), e.g., CPS Disc CentrifugeModel DC24000UHR. Unless specified otherwise, the median particle sizevalues reported and claimed herein are based on disc centrifugemeasurements.

By way of example, the abrasive particles (e.g., ceria abrasiveparticles) can have a median particle size of about 40 nm or more, e.g.,about 45 nm or more, about 50 nm or more, about 55 nm or more, about 60nm or more, about 65 nm or more, about 70 nm or more, about 75 nm ormore, or about 80 nm or more. Alternatively, or in addition, theabrasive particles can have a median particle size of about 100 nm orless, e.g., about 95 nm or less, about 90 nm or less, about 85 nm orless, about 80 nm or less, about 75 nm or less, about 70 nm or less, orabout 65 nm or less. Thus, the abrasive particles can have a medianparticle size within a range bounded by any two of the aforementionedendpoints. For example, the abrasive particles can have a medianparticle size of about 40 nm to about 100 nm, e.g., about 40 nm to about80 nm, about 40 nm to about 75 nm, about 40 nm to about 60 nm, about 50nm to about 100 nm, about 50 nm to about 80 nm, about 50 nm to about 75nm, about 50 nm to about 70 nm, about 60 nm to about 100 nm, about 60 nmto about 80 nm, about 60 nm to about 85 nm, or about 65 nm to about 75nm. Preferably, the abrasive particles have a median particle size ofabout 60 nm to about 80 nm, e.g., a median particle size of about 65 nm,a median particle size of about 70 nm, or a median particle size ofabout 75 nm.

The chemical-mechanical polishing composition can comprise any suitableamount of abrasive. If the composition comprises too little abrasive,the composition may not exhibit sufficient removal rate. In contrast, ifthe polishing composition comprises too much abrasive, the compositionmay exhibit undesirable polishing performance, may not be costeffective, and/or may lack stability. Accordingly, the abrasive can bepresent in the polishing composition at a concentration of about 5 wt. %or less, for example, about 4 wt. % or less, about 3 wt. % or less,about 2 wt. % or less, or about 1 wt. % or less. Alternatively, or inaddition, the abrasive can be present in the polishing composition at aconcentration of about 0.001 wt. % or more, for example, about 0.005 wt.% or more, about 0.01 wt. % or more, about 0.05 wt. % or more, about 0.1wt. % or more, or about 0.5 wt. % or more. Thus, the abrasive can bepresent in the polishing composition at a concentration bounded by anytwo of the aforementioned endpoints. For example, the abrasive can bepresent in the polishing composition at a concentration of about 0.001wt. % to about 5 wt. %, e.g., about 0.005 wt. % to about 4 wt. %, about0.01 wt. % to about 3 wt. %, about 0.05 wt. % to about 2 wt. %, or about0.1 wt. % to about 1 wt. %.

Typically, the polishing composition does not comprise a substantialamount of an abrasive suitable for polishing metals (e.g., copper,silver, tungsten, etc.) on the surface of a substrate. For example, thepolishing composition typically does not comprise a substantial amountof certain metal oxides (e.g., alumina) suitable for polishing a metalsurface. Typically, the polishing composition comprises less than 0.1wt. % of an abrasive other than ceria abrasive and zirconia abrasive,based on the total weight of abrasive in the polishing composition. Forexample, the polishing composition can comprise 0.05 wt. % or less of anabrasive other than a ceria abrasive and a zirconia abrasive, or 0.01wt. % or less of an abrasive other than a ceria abrasive and a zirconiaabrasive. More specifically, the polishing composition can comprise 0.05wt. % or less of a metal oxide other than ceria and zirconia, or 0.01wt. % or less of a metal oxide other than ceria and zirconia.

The abrasive desirably is suspended in the polishing composition, morespecifically in the aqueous carrier of the polishing composition. Morespecifically, when the abrasive includes particles, the abrasiveparticles desirably are suspended in the polishing composition, and theabrasive particles preferably are colloidally stable. The term colloidrefers to the suspension of abrasive particles in the aqueous carrier.Colloidal stability refers to the maintenance of that suspension overtime. In the context of this invention, abrasive particles areconsidered colloidally stable if, when the abrasive particles are placedinto a 100 mL graduated cylinder and allowed to stand unagitated for atime of 2 hours, the difference between the concentration of particlesin the bottom 50 mL of the graduated cylinder ([B] in terms of g/mL) andthe concentration of particles in the top 50 mL of the graduatedcylinder ([T] in terms of g/mL) divided by the initial concentration ofparticles in the abrasive composition ([C] in terms of g/mL) is lessthan or equal to 0.5 (i.e., {[B]−[T]}/[C]≤0.5). The value of [B]−[T]/[C]desirably is less than or equal to 0.3, and preferably is less than orequal to 0.1.

The inventive polishing composition comprises a self-stopping agent. Theself-stopping agent is a compound that facilitates a relatively highpattern removal rate and a relatively low blanket removal rate, and uponplanarizing during polishing, facilitates transitioning from a highpattern removal rate to a relatively low blanket removal rate. Withoutwishing to be bound to any particular theory, it is believed that theself-stopping agent acts as a ligand that attaches to the abrasive(e.g., to ceria or to zirconia) to facilitate self-stopping behavior byproviding steric hindrance between the abrasive and the hydrophilicoxide surface. The binding of the self-stopping agent to the abrasivecan be evaluated using any suitable technique, e.g., isothermaltitration calorimetry (ITC).

Without wishing to be bound by any particular theory, it is believedthat the self-stopping agent facilitates a non-linear response to agiven down force (DF) on tetraethoxysilane (TEOS) blanket dielectricmaterials. During polishing, pattern dielectric material experiences aneffective downforce (DF) higher than that of blanket dielectricmaterial, because contact is spread over only some portions of thepattern dielectric material which are making contact with the pad. Ahigher effective DF applied to a TEOS pattern dielectric materialresults in a “high” removal rate (e.g., pattern removal rate) polishingregime having a TEOS removal rate of about 8,000 Å/min, wherein a lowereffective DF results in a “stopping” polishing regime having a TEOSremoval rate of about 1,000 Å/min or less (e.g., blanket removal rate).The difference between the “high” regime and the “stopping” regimetypically is distinct such that for a given DF either a “high” removalrate, or a “stopping” removal rate is observed. Accordingly, it isbelieved that the self-stopping agent desirably enables a “high” removalrate (i.e., a pattern removal rate) even when the applied DF is in the“stopping” regime as determined with blanket wafers.

Moreover, it also noted that the mechanism is not solely dependent on DFsince the trench oxide removal rate on pattern dielectric material ishigher than the blanket removal rate despite having a lower effective DFin the trenches than on the blanket wafers. For example, in somepolishing applications, the concentration of the self-stopping agentplays a role in the observed effect since at low concentrations, theself-stopping agent can act as a rate enhancer (e.g., a “high” removalrate is observed) and at higher concentrations the self-stoppingbehavior is observed (e.g., a “stopping” removal rate is observed).Accordingly, some rate enhancers can have dual action. By way ofexample, when a polishing composition comprises picolinic acid in lowerconcentrations, the picolinic acid can function as a rate enhancer.However, when the polishing composition comprises picolinic acid inhigher concentrations, the picolinic acid can function as aself-stopping agent. Typically, picolinic acid functions as a rateenhancer at concentrations less than about 1000 ppm, on a weight basis(e.g., about 500 ppm, about 250 ppm, etc).

In some embodiments of the invention, the self-stopping agent is of theformula Q-B, wherein Q is a substituted or unsubstituted hydrophobicgroup, or a group imparting a steric hindrance, and B is a bindinggroup, such as, —C(O)—C—OH, —C(O)—C—C—OH or —C(O)—OH. For example, insome embodiments the invention provides a polishing compositioncomprising an abrasive, a self-stopping agent of the formula Q-B, acationic compound, and an aqueous carrier (e.g., water), wherein thepolishing composition has a pH of about 3 to about 9 (e.g., about 6.5 toabout 8.5).

In some embodiments of the invention, the self-stopping agent is of theformula Q-B, wherein Q is a substituted or unsubstituted hydrophobicgroup, or a group imparting a steric hindrance, and B is a bindinggroup, wherein the binding group has the structure: —C(O)—X—OH or—C(O)—OH. Wherein X is a C1-C2 alkyl group. When the self-stopping agentis a compound of the formula Q-B as described herein, Q can be anysuitable hydrophobic group, or any suitable group imparting sterichindrance. Suitable hydrophobic groups include saturated and unsaturatedhydrophobic groups. The hydrophobic group can be linear or branched, andcan include linear or branched alkyl groups, cycloalkyl groups, and ringstructures, including aromatic, heterocyclic, and fused ring systems.

In an embodiment, Q is selected from an alkyl group, a cycloalkyl group,an aromatic group, a heterocyclic group, a heteroaromatic group, andcombinations thereof.

Q can be an alkyl group. Suitable alkyl groups include, for example,linear or branched, saturated or unsaturated, substituted orunsubstituted hydrocarbon groups having 1 to 30 carbon atoms (e.g., aC₁-C₃₀ alkyl group, a C₁-C₂₄ alkyl group, a C₁-Cis alkyl group, a C₁-C₁₂alkyl group, or even a C₁-C₆ alkyl group), for example, at least 1carbon atom (i.e., methyl), at least 2 carbon atoms (e.g., ethyl,vinyl), at least 3 carbon atoms (e.g., propyl, isopropyl, propenyl,etc.), at least 4 carbon atoms (butyl, isobutyl, sec-butyl, butane,etc.), at least 5 carbon atoms (pentyl, isopentyl, sec-pentyl,neo-pentyl, etc.), at least 6 carbon atoms (hexyl, etc.), at least 7carbon atoms, at least 8 carbon atoms, at least 9 carbon atoms, at least10 carbon atoms, at least 11 carbon atoms, at least 12 carbon atoms, atleast 13 carbon atoms, at least 14 carbon atoms, at least 15 carbonatoms, at least 16 carbon atoms, at least 17 carbon atoms, at least 18carbon atoms, at least 19 carbon atoms, at least 20 carbon atoms, atleast 25 carbon atoms, or at least 30 carbon atoms.

A substituted group refers to a group in which one or more carbon-bondedhydrogens is replaced by a non-hydrogen atom. Illustrative substituentsinclude, for example, hydroxyl groups, keto groups, esters, amides,halogens (e.g., fluorine, chlorine, bromine, and iodine), amino groups(primary, secondary, tertiary, and/or quaternary), and combinationsthereof.

Q can be a cycloalkyl group. Suitable cycloalkyl groups include, forexample, saturated or unsaturated, substituted or unsubstitutedcycloalkyl groups having 3 to 20 carbon atoms (e.g., C₃-C₂₀ cyclicgroup). For example, suitable cycloalkyl groups include cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl,cyclononyl, and combinations thereof. In addition, suitable unsaturatedcycloalkyl groups include, for example, cyclobutene, cyclopentene,cyclohexene, and combinations thereof.

Q can be an aromatic group. Suitable aromatic groups include, forexample, substituted or unsubstituted aromatic groups having 1 to 20carbon atoms. For example, suitable aromatic groups include phenyl,benzyl, naphthyl, azulene, anthracene, pyrene, and combinations thereof.

Q can be a heteroaromatic group. A “heteroatom” is defined herein as anyatom other than carbon and hydrogen atoms. Suitableheteroatom-containing functional groups include, for example, hydroxylgroups, carboxylic acid groups, ester groups, ketone groups, aminogroups (e.g., primary, secondary, and tertiary amino groups), amidogroups, imido groups, thiol ester groups, thioether groups, nitrilegroups, nitros groups, halogen groups, and combinations thereof.

Suitable heterocyclic groups include, for example, cyclic hydrocarboncompounds containing 1 to 20 carbon atoms and containing nitrogen,oxygen, sulfur, phosphorous, boron, and combinations thereof. Theheterocyclic compound can be saturated and unsaturated, substituted orunsubstituted. A heterocyclic compound refers to a 5-, 6-, or 7-memberedring compound having one or more heteroatom atoms (e.g., N, O, S, P, orB)) contained as part of the ring system. Illustrative heterocycliccompounds include, for example, a triazole, aminotriazole,3-amino-1,2,4-triazole, 3-amino-1,2,4-triazole-5-carboxylic acid,3-amino-5-mercapto-1,2,4-triazole,4-amino-5-hydrazino-1,2,4-triazole-3-thiol, thiazole,2-amino-5-methylthiazole, 2-amino-4-thoazoleacetic acid, a heterocyclicN-oxide, 2-hydroxypyridine-N-oxide, 4-methylmorpholine-N-oxide, andpicolinic acid N-oxide, and the like. Other illustrative heterocycliccompounds include, for example, pyrone compounds, pyridine compounds,including regioisomers and stereoisomers, pyrrolidine,delta-2-pyrroline, imidazolidine, delta-2-imidazoline,delta-3-pyrazoline, pyrazolidine, piperidine, piperazine, morpholine,quinuclidine, indoline, isoindoline, chroman, isochromann, andcombinations thereof.

Suitable heteroaromatic groups include, for example, pyridine,thiophene, furane, pyrrole, 2H-pyrrole, imidazole, pyrazole, isoxazole,furazan, isothiazole, pyran(2H), pyrazine, pyrimidine, pyridazine,isobenzofuran, indolizine, indole, 3H-indole, 1H-indazole, purine,isoindole, 4aH-carbazole, carbazole, beta-carboline, 2H-chromene,4H-quinolizine, isoquinoline, quinoline, quinoxalin, 1,8-naphthyridine,phthalazine, quinazoline, cinnoline, pteridine, xanthenes, phenoxathiin,phenothiazine, phenazine, perimidine, 1,7-phenantrholine,phenanthridine, acridine, and combinations thereof.

In some embodiments, Q is substituted with one or more substituents.Suitable substituents can include, for example, any suitablecompound/group described herein. For example, suitable substituentsinclude alkyl groups, cycloalkyl groups, aryl groups, heterocyclicgroups, heteroaromatic groups, and combinations thereof.

In some embodiments, Q is unsubstituted. In other embodiments, Q is agroup that imparts a steric hindrance. For example, Q may not beparticularly hydrophobic, but may be a bulky constituent that preventschemical reactions or interactions that would otherwise occur in relatedmolecules with smaller Q groups. Without limitation, examples ofself-stopping agents having such a Q group would be maltol, ethyl maltoland kojic acid.

In some embodiments, the binding group B is selected from a carboxylicacid group, a hydroxamic acid group, a hydroxylamine group, a hydroxylgroup, a keto group, a sulfate group, a phosphate group, andcombinations thereof.

In some embodiments, the self-stopping agent Q-B is selected from kojicacid, maltol, ethyl maltol, propyl maltol, hydroxamic acid,benzhydroxamic acid, salicylhydroxamic acid, benzoic acid,3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid,sorbic acid, and combinations thereof.

In addition, the salts of the self-stopping agents of the formulationQ-B also are suitable for use in the inventive polishing compositions.

In some embodiments, the self-stopping agent is selected from kojicacid, maltol, ethyl maltol, propyl maltol, tiglic acid, angelic acid,benzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid,caffeic acid, sorbic acid, potassium sorbate, and combinations thereof.

In some embodiments, the self-stopping agent of the formulation Q-B isselected from a compound of formula (I), a compound of formula (II), acompound of formula (III), a compound of formula (IV) and combinationsthereof.

A compound of formula (I) has the following structure:

wherein R is selected from the group consisting of hydrogen, alkyl,cycloalkyl, aryl, heterocyclic alkyl, and heterocyclic aryl, each ofwhich may be substituted or unsubstituted.

A compound of formula (II) has the following structure:

wherein each of X¹-X³ is independently selected from N, O, S, a sp²hybridized carbon, and CY¹Y², wherein each of Y¹ and Y² is independentlyselected from hydrogen, hydroxyl, C₁-C₆ alkyl, halogen, and combinationsthereof, and each of Z¹-Z³ is independently selected from hydrogen,hydroxyl, C₁-C₆ alkyl, and combinations thereof, each of which may besubstituted or unsubstituted.

A compound of formula (III) has the following structure:Z—(C(X¹X²)_(n))_(p)—CO₂M  (III),wherein Z is selected from N, C₁-C₆ alkyl, C₁-C₆ alkenyl, C₁-C₆ alkynyl,and aryl (e.g., phenyl, benzyl, naphthyl, azulene, anthracene, pyrene,etc.), X¹ and X² are independently selected from hydrogen, hydroxy,amino, and C₁-C₆ alkyl, C₁-C₆ alkenyl; and wherein X¹ and X² takentogether with the attached carbon can form a sp²-hybridized carbon, n is1 or 2, p is 0-4, and M is selected from hydrogen and a suitablecounterion (e.g., a group I metal), each of which may be substituted orunsubstituted.

A compound of formula (IV) has the following structure:

where X, Y, and Z are independently selected from H, O, S, NH, and CH₂,R¹, R² and R³ are independently selected from H, alkyl, alkenyl,alkynyl, aryl, halo, and haloalkyl, and M is selected from hydrogen anda suitable counterion.

The polishing composition can comprise any suitable amount of theself-stopping agent (e.g., a compound of the formula Q-B). If thecomposition comprises too little self-stopping agent, then thecomposition may not exhibit suitable self-stopping behavior. Incontrast, if the polishing composition comprises too much self-stoppingagent, the composition may exhibit undesirable polishing performance,may not be cost effective, and/or may lack stability. Accordingly, thepolishing composition can comprise about 2 wt. % or less of theself-stopping agent, for example, about 1 wt. % or less, about 0.5 wt. %or less, about 0.1 wt. % or less, or about 0.01 wt. % or less.Alternatively, or in addition, the polishing composition can compriseabout 0.0001 wt. % or more of the self-stopping agent, for example,about 0.0005 wt. % or more, about 0.001 wt. % or more, about 0.005 wt. %or more, about 0.01 wt. % or more, or about 0.05 wt. % or more. Thus,the polishing composition can comprise the self-stopping agent at aconcentration bounded by any two of the aforementioned endpoints. Forexample, the self-stopping agent can be present in the polishingcomposition at a concentration of about 0.0001 wt. % to about 2 wt. %,e.g., about 0.0005 wt. % to about 1 wt. %, about 0.001 wt. % to about0.5 wt. %, about 0.005 wt. % to about 0.1 wt. %, or about 0.01 wt. % toabout 0.05 wt. %.

In some embodiments, the inventive polishing composition comprises about0.5 wt. % or less (e.g., about 5,000 ppm or less) of the self-stoppingagent. In some embodiments, the polishing composition comprises about2,500 ppm (0.25 wt. %) or less of the self-stopping agent, e.g., about2,000 ppm or less, about 1,500 ppm or less, about 1,000 ppm or less, orabout 500 ppm or less.

In some embodiments, the inventive polishing composition comprises aself-stopping agent in combination with a planarizing agent (i.e.,cationic compound), also referred to as a topography control agent.Without wishing to be bound by any particular theory, it is believedthat the cationic compound acts as a planarizing agent to improve thetopography of the polished substrate since the cationic compoundtypically lowers oxide removal rate by binding to the negatively chargedoxide surface. The cationic compound also improves the planarizationefficiency of the self-stopping composition under polishing conditionsof higher pH (e.g., having a pH of about 6.5 to about 8.5, having a pHof about 7.0 to 8.5).

The cationic compound may be a polymer that comprises monomers selectedfrom quaternary amines, cationic polyvinyl alcohols, cationic cellulose,and combinations thereof. Accordingly, the cationic polymer can comprisea quaternary amine, a cationic polyvinyl alcohol, a cationic cellulose,and combinations thereof.

Suitable quaternary amine monomers include, for example,vinylimidazolium, methacryloyloxyethyltrimethylammonium halide,diallyldimethylammonium halide, and combinations thereof. Thus, suitablecationic polymers include, for example, a quaternary amine selected frompoly(vinylimidazolium), a poly(methacryloyloxyethyltrimethylammonium)halide such as poly(methacryloyloxyethyltrimethylammonium) chloride(polyMADQUAT), a poly(diallyldimethylammonium) halide such aspoly(diallyldimethylammonium) chloride (polyDADMAC),poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea](i.e. Polyquaternium-2),copolymers of vinylpyrrolidone and quaternized dimethylaminoethylmethacrylate (i.e. Polyquaternium-11), copolymers of vinylpyrrolidoneand quaternized vinylimidazole (i.e. Polyquaternium-16), a terpolymer ofvinylcaprolactam, vinylpyrrolidone, and quaternized vinylimidazole (i.e.Polyquaternium-46), and 3-Methyl-1-vinylimidazolium methylsulfate-N-vinylpyrrolidone copolymer (i.e. Polyquaternium-44).Additionally, suitable cationic polymers include cationic polymers forpersonal care such as Luviquat® Supreme, Luviquat® Hold, Luviquat®UltraCare, Luviquat® FC 370, Luviquat® FC 550, Luviquat® FC 552,Luviquat® Excellence, and combinations thereof. Any combination of thecationic polymers mentioned here may be used.

In an embodiment, the cationic polymer is a quaternary amine, and thecationic polymer is a poly(methacryloyloxyethyltrimethylammonium)halide, for example, polyMADQUAT.

In an embodiment, the cationic polymer is a quaternary amine, and thecationic polymer is poly(vinylimidazolium).

The cationic polymer can be any suitable cationic polyvinyl alcohol orcationic cellulose. Preferably, the cationic polymer is a cationicpolyvinyl alcohol. For example, the cationic polyvinyl alcohol can bethe Nippon Gosei GOHSEFIMER K210™ polyvinyl alcohol product.

The cationic polymer (i.e., the quaternary amine, the cationic polyvinylalcohol, the cationic cellulose, or a combination thereof, in total),when present, can be present in the polishing composition at anysuitable concentration. Typically, the cationic polymer is present inthe polishing composition at a concentration of about 1 ppm to about 500ppm, e.g., about 1 ppm to about 475 ppm, about 1 ppm to about 450 ppm,about 1 ppm to about 425 ppm, about 1 ppm to about 400 ppm, about 1 ppmto about 375 ppm, about 1 ppm to about 350 ppm, about 1 ppm to about 325ppm, about 1 ppm to about 300 ppm, about 1 ppm to about 275 ppm, about 1ppm to about 250 ppm, about 1 ppm to about 225 ppm, about 1 ppm to about200 ppm, about 1 ppm to about 175 ppm, about 1 ppm to about 150 ppm,about 1 ppm to about 125 ppm, about 1 ppm to about 100 ppm, about 1 ppmto about 75 ppm, about 1 ppm to about 50 ppm, about 1 ppm to about 40ppm, about 1 ppm to about 25 ppm, about 5 ppm to about 225 ppm, about 5ppm to about 100 ppm, about 5 ppm to about 50 ppm, about 10 ppm to about215 ppm, about 10 ppm to about 100 ppm, about 15 ppm to about 200 ppm,about 25 ppm to about 175 ppm, about 25 ppm to about 100 ppm, or about30 ppm to about 150 ppm. Unless otherwise stated, the ppm concentrationslisted herein reflect a weight based ratio of the component to the totalweight of the polishing composition.

When the cationic polymer is poly(vinylimidazolium), the cationicpolymer preferably is present in the polishing composition at aconcentration of about 1 ppm to about 10 ppm, e.g., about 2 ppm, about 5ppm, about 6 ppm, about 7 ppm, about 8 ppm, or about 9 ppm. Morepreferably, when the cationic polymer is poly(vinylimidazolium), thecationic polymer preferably is present in the polishing composition at aconcentration of about 1 ppm to about 5 ppm, e.g., about 2 ppm, about 3ppm, or about 4 ppm.

The polishing composition can optionally comprise an additive selectedfrom an anionic copolymer of a carboxylic acid monomer, a sulfonatedmonomer, or a phosphonated monomer, and an acrylate, apolyvinylpyrrolidone, or a polyvinylalcohol (e.g., a copolymer of2-hydroxyethylmethacrylic acid and methacrylic acid); a nonionicpolymer, wherein the nonionic polymer is polyvinylpyrrolidone orpolyethylene glycol; a silane, wherein the silane is an amino silane, anureido silane, or a glycidyl silane; an N-oxide of a functionalizedpyridine (e.g., picolinic acid N-oxide); a starch; a cyclodextrin (e.g.,alpha-cyclodextrin or beta-cyclodextrin), and combinations thereof.

When the additive is a nonionic polymer, and when the nonionic polymeris polyvinylpyrrolidone, the polyvinylpyrrolidone can have any suitablemolecular weight. For example, the polyvinylpyrrolidone can have amolecular weight of about 10,000 g/mol to about 1,000,000 g/mol, e.g.,about 20,000 g/mol, about 30,000 g/mol, about 40,000 g/mol, about 50,000g/mol, or about 60,000 g/mol. When the additive is a nonionic polymer,and when the nonionic polymer is polyethylene glycol, the polyethyleneglycol can have any suitable molecular weight. For example, thepolyethylene glycol can have a molecular weight of about 200 g/mol toabout 200,000 g/mol, e.g., about 8000 g/mol, or about 100,000 g/mol.

When the additive is a silane, the silane can be any suitable aminosilane, ureido silane, or glycidyl silane. For example, the silane canbe 3-aminopropyltrimethoxysilane, 3-aminopropylsilanetriol,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilanetriol,(N,N)-dimethyl-3-aminopropyltrimethoxysilane,N-phenyl-3-aminopropyltrimethoxysilane, ureidopropyltriethoxysilane, or3-glycidopropyldimethylethoxysilane.

Preferably, when the polishing composition comprises an additive, theadditive is selected from a copolymer of 2-hydroxyethylmethacrylic acidand methacrylic acid, polyvinylpyrrolidone, aminopropylsilanetriol,picolinic acid N-oxide, starch, alpha-cyclodextrin, beta-cyclodextrin,and combinations thereof.

The additive (i.e., the anionic copolymer of a carboxylic acid monomer,a sulfonated monomer, or a phosphonated monomer, and an acrylate, apolyvinylpyrrolidone, or a polyvinylalcohol; the silane; the N-oxide ofa functionalized pyridine; the starch; the cyclodextrin; or acombination thereof, in total) can be present in the chemical-mechanicalpolishing composition at any suitable concentration. Preferably, theadditive is present in the polishing composition at a concentration ofabout 1 ppm to about 500 ppm, e.g., about 5 ppm to about 400 ppm, about10 ppm to about 400 ppm, about 15 ppm to about 400 ppm, about 20 ppm toabout 400 ppm, about 25 ppm to about 400 ppm, about 10 ppm to about 300ppm, about 10 ppm to about 250 ppm, about 30 ppm to about 350 ppm, about30 ppm to about 275 ppm, about 50 ppm to about 350 ppm, or about 100 ppmto about 300 ppm. More preferably, the additive is present in thepolishing composition at a concentration of about 1 ppm to about 300ppm, e.g., about 1 ppm to about 275 ppm, about 1 ppm to about 250 ppm,about 1 ppm to about 100 ppm, about 1 ppm to about 50 ppm, about 10 ppmto about 250 ppm, about 10 ppm to about 100 ppm, or about 35 ppm toabout 250 ppm.

The polishing composition optionally can comprise a cationic polymer asdescribed herein, in addition to one or more of the additives describedherein, i.e., one or more of an anionic copolymer of a carboxylic acidmonomer, a sulfonated monomer, or a phosphonated monomer, and anacrylate, a polyvinylpyrrolidone, or a polyvinylalcohol; a nonionicpolymer; a silane; an N-oxide of a functionalized pyridine; a starch;and a cyclodextrin. Alternatively, the polishing composition cancomprise a cationic polymer without one or more of the additivesdescribed above, i.e., without one or more of an anionic copolymer of acarboxylic acid monomer, a sulfonated monomer, or a phosphonatedmonomer, and an acrylate, a polyvinylpyrrolidone, or a polyvinylalcohol;a nonionic polymer; a silane; an N-oxide of a functionalized pyridine; astarch; and a cyclodextrin.

The polishing composition comprises an aqueous carrier. The aqueouscarrier comprises water (e.g., deionized water) and may contain one ormore water-miscible organic solvents. Examples of organic solvents thatcan be used include alcohols such as propenyl alcohol, isopropylalcohol, ethanol, 1-propanol, methanol, 1-hexanol, and the like;aldehydes such as acetylaldehyde and the like; ketones such as acetone,diacetone alcohol, methyl ethyl ketone, and the like; esters such asethyl formate, propyl formate, ethyl acetate, methyl acetate, methyllactate, butyl lactate, ethyl lactate, and the like; ethers includingsulfoxides such as dimethyl sulfoxide (DMSO), tetrahydrofuran, dioxane,diglyme, and the like; amides such as N, N-dimethylformamide,dimethylimidazolidinone, N-methylpyrrolidone, and the like; polyhydricalcohols and derivatives of the same such as ethylene glycol, glycerol,diethylene glycol, diethylene glycol monomethyl ether, and the like; andnitrogen-containing organic compounds such as acetonitrile, amylamine,isopropylamine, imidazole, dimethylamine, and the like. Preferably, theaqueous carrier is water alone, i.e., without the presence of an organicsolvent.

The inventive polishing composition has a pH of about 3 to about 9.Typically, the polishing composition has a pH of about 3 or greater.Also, the pH of the polishing composition typically is about 9 or less.For example, the polishing composition can have a pH of about 3.5 toabout 9, e.g., about 4 to about 9, about 4.5 to about 9, about 5 toabout 9, about 5.5 to about 9, about 6 to about 9, about 6.5 to about 9,about 7 to about 9, about 7.5 to about 9, about 8 to about 9, or about8.5 to about 9. Alternatively, the polishing composition can have a pHof about 3 to about 8.5, e.g., about 3 to about 8, about 3 to about 7.5,about 3 to about 7, about 3 to about 6.5, about 3 to about 6, about 3 toabout 5.5, about 3 to about 5, about 3 to about 4.5, about 3 to about 4,or about 3 to about 3.5. Thus, the polishing composition can have a pHbounded by any two of the aforementioned endpoints.

Preferably, the polishing composition has a pH of about 3 to about 5, orof about 7.0 to about 8.5. For example, in a preferred embodiment thepolishing composition comprises an abrasive, a self-stopping agent ofthe formula Q-B as described herein, and an aqueous carrier, wherein thepH of the polishing composition is about 3 to about 5.

In another preferred embodiment, the polishing composition comprises anabrasive, a self-stopping agent of the formula Q-B as described herein,a cationic polymer, and an aqueous carrier, wherein the pH of thepolishing composition is about 7.0 to about 9.0. In some preferredembodiments, the inventive polishing composition comprises an abrasive,a self-stopping agent of the formula (I) as described herein, a cationicpolymer, and an aqueous carrier, wherein the pH of the polishingcomposition is about 7.0 to about 9.0.

The polishing composition can comprise a pH-adjusting agent and a pHbuffering agent. The pH-adjusting agent can be any suitable pH-adjustingagent. For example, the pH-adjusting agent can be an alkyl amine, analcohol amine, quaternary amine hydroxide, ammonia, or a combinationthereof. In particular, the pH-adjusting agent can be triethanolamine(TEA), tetramethylammonium hydroxide (TMAH or TMA-OH), ortetraethylammonium hydroxide (TEAH or TEA-OH). In some embodiments, thepH-adjusting agent is triethanolamine.

The pH-adjusting agent can be present in the polishing composition inany suitable concentration. Desirably, the pH-adjusting agent is presentin the polishing composition at a sufficient concentration to achieveand/or maintain the pH of the polishing composition within the pH rangesset forth herein, e.g., to maintain a pH of about 3 to about 9, tomaintain a pH of about 3 to about 5, or to maintain a pH of about 7.0 toabout 8.5.

The polishing composition can contain any suitable buffering agent. Forexample, suitable buffering agents may include phosphates, sulfates,acetates, malonates, oxalates, borates, ammonium salts, azoles and thelike. In some embodiments, the buffering agent is 1H-benzotriazole.

The polishing composition may contain any suitable amount of thebuffering agent, when present. For example, the buffering agent can bepresent in the polishing composition at a concentration of about 0.0001wt. % or more, e.g., about 0.0005 wt. % or more, about 0.001 wt. % ormore, about 0.005 wt. % or more, about 0.01 wt. % or more, or about 0.1wt. % or more. Alternatively, or in addition, the buffering agent can bepresent in the polishing composition at a concentration of about 2 wt. %or less, e.g., about 1.8 wt. % or less, about 1.6 wt. % or less, about1.4 wt. % or less, about 1.2 wt. % or less, or about 1 wt. % or less.Thus, the buffering agent can be present in the polishing composition ata concentration bounded by any two of aforementioned endpoints. Forexample, the buffering agent can be present in the polishing compositionat a concentration of about 0.0001 wt. % to about 2 wt. %, e.g., about0.005 wt. % to about 1.8 wt. %, about 0.01 wt. % to about 1.6 wt. %, orabout 0.1 wt. % to about 1 wt. %.

The polishing composition optionally further comprises one or more otheradditional components. Illustrative additional components include rateenhancers, conditioners, scale inhibitors, dispersants, etc. A rateenhancer desirably is an organic carboxylic acid that activates thepolishing particle or substrate by forming hypercoordinate compounds(e.g., pentacoordinate or hexacoordinate silicon compounds). Suitablerate enhancers include, for example, picolinic acid and 4-hydroxybenzoicacid. The polishing composition can comprise a surfactant and/orrheological control agent, including viscosity enhancing agents andcoagulants (e.g., polymeric rheological control agents, such as, forexample, urethane polymers), a dispersant, a biocide (e.g., KATHON™ LX),and the like. Suitable surfactants include, for example, cationicsurfactants, anionic surfactants, anionic polyelectrolytes, nonionicsurfactants, amphoteric surfactants, fluorinated surfactants, mixturesthereof, and the like. By way of example, additional components mayinclude Brij S20 (polyethylene glycol octadecyl ether) and polyethyleneglycol (e.g. PEG8000).

The polishing composition can be prepared by any suitable technique,many of which are known to those skilled in the art. The polishingcomposition can be prepared in a batch or continuous process. Generally,the polishing composition can be prepared by combining the componentsherein in any order. The term “component” as used herein includesindividual ingredients (e.g., abrasive, self-stopping agent, cationiccompound, etc.) as well as any combination of ingredients (e.g.,abrasive, self-stopping agent, cationic compound, etc.).

For example, the self-stopping agent can be added to the aqueous carrier(e.g., water) at the desired concentration(s). The pH can then beadjusted (as desired) and the abrasive can be added to the mixture atthe desired concentration to form the polishing composition. Thepolishing composition can be prepared prior to use, with one or morecomponents added to the polishing composition just before use (e.g.,within about 1 minute before use, or within about 1 hour before use, orwithin about 7 days before use). The polishing composition also can beprepared by mixing the components at the surface of the substrate duringthe polishing operation.

The polishing composition also can be provided as a concentrate which isintended to be diluted with an appropriate amount of the aqueouscarrier, particularly water, prior to use. In such an embodiment, thepolishing composition concentrate can comprise an abrasive, aself-stopping agent, a cationic polymer (if present), and aqueouscarrier, in amounts such that, upon dilution of the concentrate with anappropriate amount of water, each component of the polishing compositionwill be present in the polishing composition in an amount within theappropriate range recited above for each component. Furthermore, as willbe understood by those of ordinary skill in the art, the concentrate cancontain an appropriate fraction of the water present in the finalpolishing composition in order to ensure that other components are atleast partially or fully dissolved in the concentrate.

While the polishing composition can be prepared well before, or evenshortly before, use, the polishing composition also can be produced bymixing the components of the polishing composition at or near thepoint-of-use. As utilized herein, the term “point-of-use” refers to thepoint at which the polishing composition is applied to the substratesurface (e.g., the polishing pad or the substrate surface itself). Whenthe polishing composition is to be produced using point-of-use mixing,the components of the polishing composition are separately stored in twoor more storage devices.

In order to mix components contained in storage devices to produce thepolishing composition at or near the point-of-use, the storage devicestypically are provided with one or more flow lines leading from eachstorage device to the point-of-use of the polishing composition (e.g.,the platen, the polishing pad, or the substrate surface). By the term“flow line” is meant a path of flow from an individual storage containerto the point-of-use of the component stored therein. The one or moreflow lines can each lead directly to the point-of-use, or, in thesituation where more than one flow line is used, two or more of the flowlines can be combined at any point into a single flow line that leads tothe point-of-use. Furthermore, any of the one or more flow lines (e.g.,the individual flow lines or a combined flow line) can first lead to oneor more of the other devices (e.g., pumping device, measuring device,mixing device, etc.) prior to reaching the point-of-use of thecomponent(s).

The components of the polishing composition can be delivered to thepoint-of-use independently (e.g., the components are delivered to thesubstrate surface whereupon the components are mixed during thepolishing process), or the components can be combined immediately beforedelivery to the point-of-use. Components are combined “immediatelybefore delivery to the point-of-use” if they are combined less than 10seconds prior to reaching the point-of-use, preferably less than 5seconds prior to reaching the point-of-use, more preferably less than 1second prior to reaching the point of use, or even simultaneous to thedelivery of the components at the point-of-use (e.g., the components arecombined at a dispenser). Components also are combined “immediatelybefore delivery to the point-of-use” if they are combined within 5 m ofthe point-of-use, such as within 1 m of the point-of-use or even within10 cm of the point-of-use (e.g., within 1 cm of the point of use).

When two or more of the components of the polishing composition arecombined prior to reaching the point-of-use, the components can becombined in the flow line and delivered to the point-of-use without theuse of a mixing device. Alternatively, one or more of the flow lines canlead into a mixing device to facilitate the combination of two or moreof the components. Any suitable mixing device can be used. For example,the mixing device can be a nozzle or jet (e.g., a high-pressure nozzleor jet) through which two or more of the components flow. Alternatively,the mixing device can be a container-type mixing device comprising oneor more inlets by which two or more components of the polishingcomposition are introduced to the mixer, and at least one outlet throughwhich the mixed components exit the mixer to be delivered to thepoint-of-use, either directly or via other elements of the apparatus(e.g., via one or more flow lines). Furthermore, the mixing device cancomprise more than one chamber, each chamber having at least one inletand at least one outlet, wherein two or more components are combined ineach chamber. If a container-type mixing device is used, the mixingdevice preferably comprises a mixing mechanism to further facilitate thecombination of the components. Mixing mechanisms are generally known inthe art and include stirrers, blenders, agitators, paddled baffles, gassparger systems, vibrators, etc.

The invention also provides a method of chemically-mechanicallypolishing a substrate using the inventive CMP composition describedherein. In an embodiment, the invention provides a method ofchemically-mechanically polishing a substrate comprising (i) providing asubstrate, wherein the substrate comprises a pattern dielectric layer ona surface of the substrate, wherein the pattern dielectric layercomprises a raised area of dielectric material and a trench area ofdielectric material, and wherein the initial step height of the patterndielectric layer is the difference between the height of the raised areaof dielectric material and the height of the trench area of dielectricmaterial, (ii) providing a polishing pad, (iii) providing thechemical-mechanical polishing composition described herein, (iv)contacting the substrate with the polishing pad and thechemical-mechanical polishing composition, and (v) moving the polishingpad and the chemical-mechanical polishing composition relative to thesubstrate to abrade at least a portion of the pattern dielectric layeron a surface of the substrate to polish the substrate.

More specifically, the invention provides a method ofchemically-mechanically polishing a substrate comprising (i) providing asubstrate, wherein the substrate comprises a pattern dielectric layer ona surface of the substrate, wherein the pattern dielectric layercomprises a raised area of dielectric material and a trench area ofdielectric material, and wherein the initial step height of the patterndielectric layer is the difference between the height of the raised areaof dielectric material and the height of the trench area of dielectricmaterial, (ii) providing a polishing pad, (iii) providing achemical-mechanical polishing composition comprising (a) an abrasive,(b) a self-stopping agent of the formula Q-B, wherein Q is a substitutedor unsubstituted hydrophobic group, or a group imparting a sterichindrance, B is a binding group, wherein the binding group has thestructure, C(O)—X—OH or —C(O)—OH, wherein X is a C1-C2 alkyl group; (c)an aqueous carrier, (d) optionally, a cationic polymer, wherein thepolishing composition has a pH of about 3 to about 9, (iv) contactingthe substrate with the polishing pad and the chemical-mechanicalpolishing composition, and (v) moving the polishing pad and thechemical-mechanical polishing composition relative to the substrate toabrade at least a portion of the pattern dielectric layer on a surfaceof the substrate to polish the substrate.

The invention also provides a method of chemically-mechanicallypolishing a substrate comprising (i) providing a substrate, wherein thesubstrate comprises a pattern dielectric layer on a surface of thesubstrate, wherein the pattern dielectric layer comprises a raised areaof dielectric material and a trench area of dielectric material, andwherein the initial step height of the pattern dielectric layer is thedifference between the height of the raised area of dielectric materialand the height of the trench area of dielectric material, (ii) providinga polishing pad, (iii) providing a chemical-mechanical polishingcomposition comprising (a) an abrasive comprising ceria, (b) aself-stopping agent selected from kojic acid, maltol, caffeic acid,crotonic acid, tiglic acid, 2-pentenoic acid, 2-hydroxynicotinic acid,ethyl maltol, potassium sorbate, sorbic acid, deferiprone, valeric acidand combinations thereof, and (c) an aqueous carrier, wherein thepolishing composition has a pH of about 3 to about 9, (iv) contactingthe substrate with the polishing pad and the chemical-mechanicalpolishing composition, and (v) moving the polishing pad and thechemical-mechanical polishing composition relative to the substrate toabrade at least a portion of the pattern dielectric layer on a surfaceof the substrate to polish the substrate.

The invention also provides a method of chemically-mechanicallypolishing a substrate comprising (i) providing a substrate, wherein thesubstrate comprises a pattern dielectric layer on a surface of thesubstrate, wherein the pattern dielectric layer comprises a raised areaof dielectric material and a trench area of dielectric material, andwherein the initial step height of the pattern dielectric layer is thedifference between the height of the raised area of dielectric materialand the height of the trench area of dielectric material, (ii) providinga polishing pad, (iii) providing a chemical-mechanical polishingcomposition comprising (a) an abrasive, (b) a self-stopping agentselected from a compound of formula (I),

wherein R is selected from the group consisting of hydrogen, alkyl,cycloalkyl, aryl, heterocyclic alkyl, and heterocyclic aryl, each ofwhich may be substituted or unsubstituted, (c) an aqueous carrier, (d) acationic polymer, wherein the polishing composition has a pH of about 7to about 9, (iv) contacting the substrate with the polishing pad and thechemical-mechanical polishing composition, and (v) moving the polishingpad and the chemical-mechanical polishing composition relative to thesubstrate to abrade at least a portion of the pattern dielectric layeron a surface of the substrate to polish the substrate.

The invention also provides a method of chemically-mechanicallypolishing a substrate comprising (i) providing a substrate, wherein thesubstrate comprises a pattern dielectric layer on a surface of thesubstrate, wherein the pattern dielectric layer comprises a raised areaof dielectric material and a trench area of dielectric material, andwherein the initial step height of the pattern dielectric layer is thedifference between the height of the raised area of dielectric materialand the height of the trench area of dielectric material, (ii) providinga polishing pad, (iii) providing a chemical-mechanical polishingcomposition comprising (a) an abrasive, (b) a self-stopping agentselected from a compound of formula (II), (III) or (IV), wherein,

wherein each of X¹-X³ is independently selected from N, O, S, a sp²hybridized carbon, and CY¹Y², wherein each of Y¹ and Y² is independentlyselected from hydrogen, hydroxyl, C₁-C₆ alkyl, halogen, and combinationsthereof, and each of Z¹-Z³ is independently selected from hydrogen,hydroxyl, C₁-C₆ alkyl, and combinations thereof, each of which may besubstituted or unsubstituted.Z—(C(X¹X²)_(n))_(p)—CO₂M  (III),wherein Z is selected from N, C₁-C₆ alkyl, C₁-C₆ alkenyl, C₁-C₆ alkynyl,and aryl (e.g., phenyl, benzyl, naphthyl, azulene, anthracene, pyrene,etc.), X¹ and X² are independently selected from hydrogen, hydroxy,amino, and C₁-C₆ alkyl, C₁-C₆ alkenyl, and wherein X¹ and X² takentogether with the attached carbon can form a sp²-hybridized carbon, n is1 or 2, p is 0-4, and M is selected from hydrogen and a suitablecounterion (e.g., a group I metal), each of which may be substituted orunsubstituted,

where X, Y, and Z are independently selected from H, O, S, NH, and CH₂,R¹, R² and R³ are independently selected from H, alkyl, alkenyl,alkynyl, aryl, halo, and haloalkyl, and M is selected from hydrogen anda suitable counterion, (c) an aqueous carrier, wherein the polishingcomposition has a pH of about 3 to about 9, (iv) contacting thesubstrate with the polishing pad and the chemical-mechanical polishingcomposition, and (v) moving the polishing pad and thechemical-mechanical polishing composition relative to the substrate toabrade at least a portion of the pattern dielectric layer on a surfaceof the substrate to polish the substrate.

The invention also provides a method of chemically-mechanicallypolishing a substrate comprising (i) providing a substrate, wherein thesubstrate comprises a pattern dielectric layer on a surface of thesubstrate, wherein the pattern dielectric layer comprises a raised areaof dielectric material and a trench area of dielectric material, andwherein the initial step height of the pattern dielectric layer is thedifference between the height of the raised area of dielectric materialand the height of the trench area of dielectric material, (ii) providinga polishing pad, (iii) providing a chemical-mechanical polishingcomposition comprising (a) an abrasive comprising ceria, (b) aself-stopping agent selected from hydroxamic acids such asacetohydroxamic acid, benzhydroxamic acid, salicylhydroxamic acid andcombinations thereof, (c) a cationic polymer, and (d) an aqueouscarrier, wherein the polishing composition has a pH of about 7 to about9, (iv) contacting the substrate with the polishing pad and thechemical-mechanical polishing composition, and (v) moving the polishingpad and the chemical-mechanical polishing composition relative to thesubstrate to abrade at least a portion of the pattern dielectric layeron a surface of the substrate to polish the substrate.

The polishing compositions of the invention are useful for polishing anysuitable substrate. The polishing compositions are particularly usefulin the polishing of a substrate comprising a silicon oxide layer.Suitable substrates include, but are not limited to, flat paneldisplays, integrated circuits, memory or rigid disks, metals,semiconductors, inter-layer dielectric (ILD) devices,microelectromechanical systems (MEMS), 3D NAND devices, ferroelectrics,and magnetic heads. The polishing composition is particularlywell-suited for planarizing or polishing a substrate that has undergoneshallow trench isolation (STI) processing. Desirably, the substrateincludes a dielectric-containing (e.g., silicon oxide-containing)surface, especially one having a region of pattern dielectric materialthat includes raised dielectric areas separated by trench areas ofdielectric material. The substrate can further comprise at least oneother layer, e.g., an insulating layer. The insulating layer can be ametal oxide, porous metal oxide, glass, organic polymer, fluorinatedorganic polymer, or any other suitable high or low-K insulating layer.The insulating layer can comprise, consist essentially of, or consist ofsilicon oxide, silicon nitride, or combinations thereof. The siliconoxide layer can comprise, consist essentially of, or consist of anysuitable silicon oxide, many of which are known in the art. For example,the silicon oxide layer can comprise tetraethoxysilane (TEOS), highdensity plasma (HDP) oxide, borophosphosilicate glass (BPSG), highaspect ratio process (HARP) oxide, spin on dielectric (SOD) oxide,chemical vapor deposition (CVD) oxide, plasma-enhanced tetraethyl orthosilicate (PETEOS), thermal oxide, or undoped silicate glass. Thesubstrate can further comprise a metal layer. The metal can comprise,consist essentially of, or consist of any suitable metal, many of whichare known in the art, such as, for example, copper, tantalum, tungsten,titanium, platinum, ruthenium, iridium, aluminum, nickel, orcombinations thereof.

In accordance with the invention, a substrate can be planarized orpolished with the polishing composition described herein by any suitabletechnique. The polishing method of the invention is particularly suitedfor use in conjunction with a chemical-mechanical polishing (CMP)apparatus. Typically, the CMP apparatus comprises a platen, which, whenin use, is in motion and has a velocity that results from orbital,linear, or circular motion, a polishing pad in contact with the platenand moving with the platen when in motion, and a carrier that holds asubstrate to be polished by contacting and moving relative to thesurface of the polishing pad. The polishing of the substrate takes placeby the substrate being placed in contact with a polishing composition ofthe invention and typically a polishing pad and then abrading at least aportion of the surface of the substrate, e.g., the silicon oxide, or oneor more of the substrate materials described herein, with the polishingcomposition and typically the polishing pad to polish the substrate. Anysuitable polishing conditions can be used to polish a substrateaccording to the invention.

A substrate can be planarized or polished with the chemical-mechanicalpolishing composition in conjunction with any suitable polishing pad(e.g., polishing surface). Suitable polishing pads include, for example,woven and non-woven polishing pads. Moreover, suitable polishing padscan comprise any suitable polymer of varying density, hardness,thickness, compressibility, ability to rebound upon compression, andcompression modulus. Suitable polymers include, for example,polyvinylchloride, polyvinylfluoride, nylon, fluorocarbon,polycarbonate, polyester, polyacrylate, polyether, polyethylene,polyamide, polyurethane, polystyrene, polypropylene, coformed productsthereof, and mixtures thereof.

Although the inventive compositions and methods exhibit self-stoppingbehavior, the CMP apparatus can further comprise an in situ polishingendpoint detection system, many of which are known in the art.Techniques for inspecting and monitoring the polishing process byanalyzing light or other radiation reflected from a surface of theworkpiece are known in the art. Such methods are described, for example,in U.S. Pat. Nos. 5,196,353, 5,433,651, 5,609,511, 5,643,046, 5,658,183,5,730,642, 5,838,447, 5,872,633, 5,893,796, 5,949,927, and 5,964,643.Desirably, the inspection or monitoring of the progress of the polishingprocess with respect to a workpiece being polished enables thedetermination of the polishing end-point, i.e., the determination ofwhen to terminate the polishing process with respect to a particularworkpiece.

For a substrate of any type of device, the substrate surface can includea continuous yet structured (non-planar, non-smooth) layer of dielectricmaterial that has been placed over a lower layer that also includessurface structure or topography. This structured, non-planar region ofthe dielectric material surface is referred to as “pattern dielectric.”It results from dielectric material being placed over the unevenstructure of the lower layer to fill trenches or holes present in thelower layer. To ensure complete filling of all trenches or holes, etc.,and full coverage over the surface of the lower layer that contains thetrenches or holes, etc., the dielectric material is deposited in anexcess amount. The dielectric material will conform to the uneventopography of the lower layer, producing a deposited continuousdielectric surface characterized by raised areas separated by trenches.The raised areas will be the locations of active polishing and materialremoval, meaning the location from which most of the dielectric materialis removed. The pattern dielectric material also is characterized bywhat is referred to as a “step height,” which is the height of thedielectric material of the raised areas relative to the height of thedielectric material at the adjacent trenches.

The inventive polishing composition is particularly well suited forplanarizing or polishing a substrate that has undergone shallow trenchisolation (STI) or a similar process, whereby dielectric is coated overa structured lower layer to produce regions of pattern dielectricmaterial. For a substrate that has undergone shallow trench isolation,typical step heights can be in a range from about 1,000 angstroms toabout 7,000 angstroms.

Certain embodiments of the described polishing composition are alsouseful for planarizing or polishing a substrate that is an in-process 3DNAND flash memory device. In such substrates, a lower layer is made ofsemiconductor layer that includes trenches, holes, or other structuresthat have a high aspect ratio, such as an aspect ratio of at least 10:1,30:1, 60:1 or 80:1. When a surface having structures of such high aspectratios is coated by dielectric material, the resultant patterndielectric will exhibit a high step height, such as a step height thatis substantially greater than about 7,000 angstroms, e.g., greater thanabout 10,000 angstroms, greater than about 20,000 angstroms, greaterthan about 30,000 angstroms, or greater than about 40,000 angstroms, ormore.

The dielectric material of any of the devices described herein maycomprise, consist essentially of, or consist of any suitable dielectricmaterial, many of which are well known, including various forms ofsilicon oxide and silicon oxide-based dielectric materials. For example,a dielectric material that includes silicon oxide or silicon oxide-baseddielectric layer can comprise, consist of, or consist essentially of anyone or more of: tetraethoxysilane (TEOS), high density plasma (HDP)oxide, phosphosilicate glass (PSG), borophosphosilicate glass (BPSG),high aspect ratio process (HARP) oxide, spin on dielectric (SOD) oxide,chemical vapor deposition (CVD) oxide, plasma-enhanced tetraethyl orthosilicate (PETEOS), thermal oxide, or undoped silicate glass. In thepast, some examples of substrates that require planarization of patterndielectric have been prepared to include a silicon nitride layer (e.g.,a “silicon nitride cap” or “liner”) at a location below active polishingregions of pattern dielectric material, e.g., a “cap” over a landsurface of a structured semiconductor layer. The silicon nitride isdesigned to cause a stop to polishing and removal of dielectric materialat the active region, upon reaching the silicon nitride layer. Thesilicon nitride layer functions to halt removal of material in apolishing step in a manner intended to reduce trench loss and dishing infinal topography. This step, however, adds significant cost to amanufacturing process and still may not fully prevent dishing.

According to methods of the present invention, a substrate may include asilicon nitride liner located at locations of intended ends of adielectric polishing and removal step. In other embodiments, a substratedoes not require and can optionally and preferably exclude a siliconnitride “liner” or “cap” disposed at locations of an end a step ofremoving dielectric from an active area.

Desirably, pattern dielectric material is planarized and polished toreduce initial step height between raised areas (having initial height)and trenches (having initial trench thickness). To accomplish thisplanarization effectively and efficiently, the inventive method has ahigh removal rate of raised areas of (active) pattern dielectricmaterial, along with a substantially lower removal rate of dielectricmaterial of trenches. Most preferably, the inventive method alsoexhibits self-stopping behavior.

During CMP polishing or planarization, dielectric material is removedfrom raised areas, and from trenches in smaller amounts. Duringpolishing, the height of raised areas decreases to eventually beessentially level with the height of trenches. This can mean, forexample, that step height is reduced to less than 1,000 angstroms, e.g.,less than 900 angstroms, less than 500 angstroms, less than 300angstroms, or less than 250 angstroms. Reducing the height of raisedareas removes the pattern of raised areas among the trenches,effectively removing the pattern and converting the pattern to a fieldof planarized dielectric, i.e., “blanket dielectric or “blanket oxide,”meaning a substantially planarized region of dielectric material.

Depending on the substrate being polished, an initial step height may beat least 1,000 angstroms, e.g., at least 2,000 angstroms, or at least5,000 angstroms, and may be substantially greater, such as greater than7,000 angstroms, e.g., at least 10,000 angstroms, at least 20,000angstroms, at least 30,000 angstroms, or at least 40,000 angstroms,measured before beginning a step of CMP processing. After polishing,step height is reduced and trench thickness is reduced.

FIG. 1 depicts an exemplary substrate having an initial step height (h₀)and an initial trench thickness (t₀). The material of the step heightcan be mostly dielectric such as TEOS, BPSG, or other amorphoussilica-containing materials. The key step in 3D NAND dielectric (andother bulk oxide removal) processing is to reduce step height (h₁)(e.g., to less than about 1,000 Å, or to less than about 900 Å) withminimal trench loss (t₀−t₁). For good planarization efficiency, thefinal step height must be achieved without significant trench loss. Thisrequires a polishing composition with a higher removal rate on theactive (i.e., raised) areas than at the trench area. Additionally,preferred polishing compositions will result in a “self-stopping” or“stop on planar” behavior, to allow for more effective final polishingthat does not cause over-polishing. Desirably, the inventive polishingcomposition has a much higher pattern removal rate (removal rate atactive areas) compared to the removal rate on blanket (substantiallysmooth) dielectric material.

Removal rate of dielectric material at active areas is referred to as aremoval rate of pattern material (e.g., pattern oxide) or “patternremoval rate” or “active removal rate.” The pattern removal rateachieved using a method and polishing composition as described hereincan be any suitable rate, and for any given process and substrate willdepend in great part on the dimensions (e.g., pitch and width) of theraised areas. According to preferred methods, the removal rate ofpattern dielectric material can be at least about 2,000 angstroms perminute, preferably at least about 4,000 angstroms per minute, e.g., atleast about 5,000 angstroms per minute, at least about 6,000 angstromsper minute, at least about 10,000 angstroms per minute, at least about14,000 angstroms per minute, or at least about 15,000 angstroms perminute.

According to preferred methods, the pattern dielectric can be processedto a planarized surface by CMP processing of the pattern dielectric fora time that is less than 5 minutes, e.g., less than 3 minutes, less than2 minutes, or less than 1 minute. This can be accomplished for asubstrate with pattern dielectric material that includes a step heightof at least 7,000 angstroms, e.g., at least 10,000 angstroms, at least20,000 angstroms, at least 30,000 angstroms, or at least 40,000angstroms. The surface is considered to be effectively planarized uponachieving a reduced (by polishing) step height (i.e., a “remaining” stepheight) of less than 1,000 angstroms. Thus, the inventive polishingcomposition and methods can provide a remaining step height of less than1,000 angstroms, e.g., less than 900 angstroms, less than 500 angstroms,less than 300 angstroms, or less than 250 angstroms.

Also, according to preferred polishing methods using polishingcompositions as described herein, trench loss can be reduced andplanarization efficiency can be improved relative to polishingcompositions that do not contain a self-stopping agent as describedherein (e.g., a compound of the formula Q-B). Trench loss refers to thedifference between a thickness of a trench (t₀) before CMP processing,less the thickness of the trench after CMP processing (t₁), i.e., trenchloss equals t₀-t₁ (for a given processing time or result) (FIG. 1).Preferably, the amount of trench loss that will occur during polishingto planarization (defined, e.g., by a “remaining” step height of lessthan 1,000 angstroms, e.g., less than 900 angstroms, less than 500angstroms, less than 300 angstroms, or less than 250 angstroms), or fora given amount of processing time, can be decreased by the presence of aself-stopping agent as described herein in a polishing composition asdescribed herein. Thus, the polishing method described herein willresult in a trench loss that is substantially less than (e.g., at least10 percent less than) the trench loss that would occur using the sameprocess conditions and equipment to polish the same type of substratewith a polishing composition that is similar but does not contain aself-stopping agent as described herein (e.g., a polishing compositionthat does not contain a compound of the formula Q-B). Desirably, theinventive method of polishing a substrate provides a trench loss of lessthan about 2,000 angstroms (e.g., less than about 1,500 angstroms, lessthan about 1,000 angstroms, less than about 500 angstroms, or less thanabout 250 angstroms).

A lower trench loss can be reflected in planarization efficiency, whichrefers to step height reduction (A) divided by trench loss (A).According to preferred methods of the present invention, planarizationefficiency can be improved by the presence of a self-stopping agent asdescribed herein in a polishing composition as described herein. Thus,the polishing method described herein will result in a planarizationefficiency that is substantially greater than (e.g., at least 10 percentgreater than) the planarization efficiency that would occur usingidentical process conditions and equipment to polish the same type ofsubstrate with a polishing composition that is similar but does notcontaining a self-stopping agent as described herein (e.g., a polishingcomposition that does not contain a compound of the formula Q-B).Desirably, the inventive method of polishing a substrate provides aplanarization efficiency of at least about 2.0, preferably at leastabout 3.0, such as at least about 3.5.

Preferred methods also can exhibit self-stopping behavior, meaning thatthe removal rate of dielectric material from blanket dielectric material(upon reaching a step height of less than 1,000 angstroms, less than 900angstroms, less than 500 angstroms, less than 300 angstroms, or lessthan 200 angstroms) (i.e., the “blanket removal rate”) is significantlylower than the removal rate of pattern dielectric material.Self-stopping behavior is considered to occur if a removal rate ofblanket dielectric material is less than about 1,000 angstroms perminute. Thus, in a preferred embodiment, the inventive method provides ablanket dielectric material removal rate of less than about 1,000angstroms per minute, e.g., less than about 800 angstroms per minute,less than about 500 angstroms per minute, less than about 300 angstromsper minute, or less than about 200 angstroms per minute.

By another measure, self-stopping behavior may be measured by comparingthe removal rate of blanket dielectric material to the removal rate ofpattern dielectric material. A low ratio of blanket removal rate topattern removal rate indicates good self-stopping behavior. Thus, in apreferred embodiment, the ratio of the removal rate of blanketdielectric material to the removal rate of pattern dielectric materialis less than about 1, e.g., less than about 0.5, less than about 0.3, orless than about 0.1. Accordingly, the inventive polishing method willresult in a ratio of blanket removal rate to pattern removal rate thatis substantially less than (e.g., at least about 10 percent less than)the ratio of blanket removal rate to pattern removal rate that wouldoccur using the same process conditions and equipment to polish the sametype of substrate with a polishing composition that is similar but doesnot contain a self-stopping agent as described herein (e.g. a polishingcomposition that does not contain a compound of the formula Q-B).

In an embodiment, the invention provides a method wherein the patterndielectric layer includes an initial step height of at least about 1,000angstroms, wherein the method comprises reducing the initial step heightto less than about 900 angstroms during polishing to produce aplanarized dielectric, and wherein the removal rate of the planarizeddielectric is less than about 1,000 angstroms per minute.

In an embodiment, the present invention provides a method comprisingremoving at least about 10,000 angstroms of the raised area ofdielectric material from the surface of the pattern dielectric layer.

In an embodiment, the present invention provides a method wherein theratio of the removal rate of the raised area of dielectric material tothe removal rate of the trench area of dielectric material is greaterthan about 5, preferably greater than about 10, greater than about 15,or greater than about 20.

In an embodiment, the present invention provides a method wherein theremoval rate of the raised area of dielectric material is greater thanabout 1000 angstroms per minute. Thus, in a preferred embodiment, theremoval rate of the raised area of dielectric material is greater thanabout 2,000 angstroms per minute, e.g., greater than about 4,000angstroms per minute, greater than about 5,000 angstroms per minute,greater than about 6,000 angstroms per minute, greater than about 10,000angstroms per minute, or greater than about 15,000 angstroms per minute.

In an embodiment, the present invention provides a method wherein thepattern dielectric layer comprises dielectric material selected fromsilicon oxide, tetraethoxysilane, phosphosilicate glass,borophosphosilicate glass, and combinations thereof.

EMBODIMENTS

(1) In embodiment (1) is presented a chemical-mechanical polishingcomposition comprising (a) an abrasive, (b) a self-stopping agent of theformula Q-B, wherein Q is a substituted or unsubstituted hydrophobicgroup, or a group imparting a steric hindrance, B is a binding group,wherein the binding group has the structure; —C(O)—X—OH or —C(O)—OH,wherein X is a C1-C2 alkyl group, (for example, any compound of formulas(II), (III) and (IV)); and (c) an aqueous carrier, wherein the polishingcomposition has a pH of about 3 to about 9.

(2) In embodiment (2) is presented the polishing composition ofembodiment (1), wherein the abrasive is selected from ceria, zirconia,and combinations thereof.

(3) In embodiment (3) is presented the polishing composition ofembodiment (2), wherein the abrasive is ceria.

(4) In embodiment (4) is presented the polishing composition of any oneof embodiments (1)-(3), wherein the abrasive is present in the polishingcomposition at a concentration of about 0.001 wt. % to about 5 wt. %.

(5) In embodiment (5) is presented the polishing composition of any oneof embodiments (1)-(4), wherein Q is selected from an alkyl group, acycloalkyl group, an aromatic group, a heterocyclic group, aheteroaromatic group, and combinations thereof.

(6) In embodiment (6) is presented the polishing composition ofembodiment (5), wherein Q is substituted with one or more groupsselected from a hydroxyl group, an alkyl group, a halogen, an aminegroup, or any combination thereof.

(7) In embodiment (7) is presented the polishing composition ofembodiment (1), wherein Q-B is selected from maltol, kojic acid,crotonic acid, tiglic acid, 2-pentenoic acid, valeric acid, benzoicacid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeicacid, ethyl maltol, potassium sorbate, sorbic acid, and combinationsthereof.

(8) In embodiment (8) is presented the polishing composition of any oneof embodiments (1)-(7), wherein the self-stopping agent is present inthe polishing composition at a concentration of about 0.5 wt. % or less.

(9) In embodiment (9) is presented the polishing composition of any oneof embodiments (1)-(8), further comprising a cationic polymer.

(10) In embodiment (10) is presented the polishing composition ofembodiment (9), wherein the cationic polymer comprises monomers selectedfrom quaternary amines, cationic polyvinyl alcohols, cationic cellulose,and combinations thereof.

(11) In embodiment (11) is presented the polishing composition ofembodiment (10), wherein the cationic polymer comprises quaternary aminemonomers, and wherein the quaternary amine monomers are selected fromvinylimidazolium, methacryloyloxyethyltrimethylammonium halide,diallyldimethylammonium halide, and combinations thereof.

(12) In embodiment (12) is presented the polishing composition ofembodiment (9), wherein the cationic polymer is selected frompoly(vinylimidazolium), poly(methacryloyloxyethyltrimethylammonium)chloride, poly(diallyldimethylammonium) chloride, polyquaternium-2, andcombinations thereof.

(13) In embodiment (13) is presented the polishing composition of anyone of embodiments (1)-(12), wherein the polishing composition has a pHof about 6.5 to about 8.5.

(14) In embodiment (14) is presented the polishing composition of anyone of embodiments (1)-(12), wherein the polishing composition has a pHof about 3 to about 5.

(15) In embodiment (15) is presented the polishing composition of anyone of embodiments (1)-(14), further comprising a rate enhancer and/or apH buffer.

(16) In embodiment (16) is presented a chemical-mechanical polishingcomposition comprising (a) an abrasive comprising ceria, (b) aself-stopping agent selected from kojic acid, crotonic acid, tiglicacid, valeric acid, 2-pentenoic acid, maltol, benzoic acid,3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, caffeic acid,ethyl maltol, potassium sorbate, sorbic acid, and combinations thereof,and (c) an aqueous carrier, wherein the polishing composition has a pHof about 3 to about 9.

(7) In embodiment (17) is presented the polishing composition ofembodiment (16), wherein the polishing composition has a pH of about 3to about 5.

(18) In embodiment (18) is presented the polishing composition ofembodiment (16), further comprising a planarizing agent comprising acationic polymer selected from poly(vinylimidazolium),poly(methacryloyloxyethyltrimethylammonium) chloride,poly(diallyldimethylammonium) chloride, polyquaternium-2, andcombinations thereof.

(19) In embodiment (19) is presented the polishing composition ofembodiment (18), wherein the polishing composition has a pH of about 6.5to about 8.5.

(20) In embodiment (20) is presented a chemical-mechanical polishingcomposition comprising (a) an abrasive comprising ceria, (b) aself-stopping agent selected from a compound of formula (I):

wherein R is selected from the group consisting of hydrogen, alkyl,cycloalkyl, aryl, heterocyclic alkyl, and heterocyclic aryl, each ofwhich may be substituted or unsubstituted; (c) a cationic compoundselected from aluminum salts, 2-(dimethylamino)ethyl methacrylate,diallyldimethylammonium, poly(vinylimidazolium),poly(methacryloyloxyethyltrimethylammonium) halide,poly(diallyldimethylammonium) halide, polyquaternium-2,Polyquaternium-11, Polyquaternium-16, Polyquaternium-46,Polyquaternium-44, Luviquat Supreme, Luviquat Hold, Luviquat UltraCare,Luviquat FC 370, Luviquat FC 550, Luviquat FC 552, Luviquat Excellence,and combinations thereof, and (d) an aqueous carrier, wherein thepolishing composition has a pH of about 7 to about 9.

(21) In embodiment (21) is presented the polishing composition ofembodiment (20), wherein the polishing composition has a pH of about 7to about 9.

(22) In embodiment (22) is presented a method of chemically-mechanicallypolishing a substrate comprising (i) providing a substrate, wherein thesubstrate comprises a pattern dielectric layer on a surface of thesubstrate, wherein the pattern dielectric layer comprises a raised areaof dielectric material and a trench area of dielectric material, andwherein the initial step height of the pattern dielectric layer is thedifference between the height of the raised area of dielectric materialand the height of the trench area of dielectric material, (ii) providinga polishing pad, (iii) providing the chemical-mechanical polishingcomposition of any one embodiments (1)-(21), (iv) contacting thesubstrate with the polishing pad and the chemical-mechanical polishingcomposition, and (v) moving the polishing pad and thechemical-mechanical polishing composition relative to the substrate toabrade at least a portion of the pattern dielectric layer on a surfaceof the substrate to polish the substrate.

(23) In embodiment (23) is presented the polishing method of embodiment(22), wherein the pattern dielectric layer includes an initial stepheight of at least about 1,000 angstroms, wherein the method comprisesreducing the initial step height to less than about 900 angstroms duringpolishing to produce a planarized dielectric, and wherein the removalrate of the planarized dielectric is less than about 1,000 angstroms perminute.

(24) In embodiment (24) is presented the polishing method of embodiment(22) or embodiment (23), wherein the method comprises removing at leastabout 10,000 angstroms of the raised area of dielectric material fromthe of the pattern dielectric layer.

(25) In embodiment (25) is presented the polishing method of any one ofembodiments (22)-(24), wherein the ratio of the removal rate of theraised area of dielectric material to the removal rate of the trencharea of dielectric material is greater than about 5.

(26) In embodiment (26) is presented the polishing method of any one ofembodiments (22)-(25), wherein the removal rate of the raised area ofdielectric material is greater than about 1,000 angstroms per minute.

(27) In embodiment (27) is presented the polishing method of any one ofembodiments (22)-(26), wherein the pattern dielectric layer comprisesdielectric material selected from silicon oxide, tetraethoxysilane,phosphosilicate glass, borophosphosilicate glass, and combinationsthereof.

EXAMPLES

The following examples further illustrate the invention but, of course,should not be construed as in any way limiting its scope.

The following abbreviations are used in the examples PEG8000 refers topolyethylene glycol having a molecular weight of 8,000 g/mol; pMADQUATrefers to polyMADQUAT; SHA refers to salicylhydroxamic acid; BHA refersto benzhydroxamic acid; BTA refers to 1H-benzotriazole; TEA refers totriethanolamine; POU refers to point-of-use; RR refers to removal rate;AA refers to Active Area; TA refers to Trench Area; BW refers to TEOSblanket wafer; and SH refers to step-height.

Example 1

This example demonstrates the effect of a self-stopping agent,optionally in combination with a cationic compound, on polishingperformance in polishing compositions comprising the same.

Pattern substrates were polished with fourteen polishing compositions(i.e., Polishing Compositions 1A-1N). Polishing Compositions 1A-1N wereprepared by mixing Abrasive Compositions C1 and C2 (described below inTable 1) with Additive Formulations F1-F15 (described below in Table 2)in a 7:3 ratio by volume.

Abrasive Compositions C1 and C2 contained ceria abrasive, picolinicacid, and water, as set forth in Table 1. The HC60 and HC30 ceriaabrasives are commercially available from Rhodia. The H-30 ceriaabrasive is a wet process ceria described in a previous application(U.S. Published Patent Application 2016/0257855). Abrasive compositionsC1 and C2 each had a pH of 4.2.

TABLE 1 Abrasive Compositions Ceria Picolinic Composition (wt. %) acid(ppm) C1 HC60 (0.14) 714 HC30 (0.14) C2 H-30 (0.29) 500

Additive Formulations F4-F15 contained cationic compound (pMADQUAT),self-stopping agent (SHA or BHA), and additive (BTA) as set forth inTable 2. The pH of each of Additive Formulations F3-F15 was adjustedusing triethanolamine (TEA). Additive Formulations F1 and F2 did notcontain a base and had a pH of 4.2.

TABLE 2 Additive Formulations Self- Cationic Stopping Additional For-Compound Agent Components Formulation mulation (ppm) (ppm) (wt. %) pH F1— SHA — 4.2 (840) F2 — BHA PEG8000 4.2 (1,250) (0.835) F3 — SHA — 8.2(840) F4 pMADQUAT SHA BTA (0.16) 8.2 (140) (840) F5 pMADQUAT SHA BTA(0.16) 8.2 (170) (1,030) F6 pMADQUAT SHA BTA (0.16) 9.1 (170) (1,030) F7pMADQUAT SHA BTA (0.16) 8.2 (170) (1,350) F8 pMADQUAT SHA BTA (0.16) 8.2(200) (1,400) F9 pMADQUAT SHA BTA (0.16) 7.5 (200) (1,400) F10 pMADQUATBHA BTA (0.16) 8.2 (200) (840) F11 pMADQUAT SHA BTA (0.16) 8.2 (200)(1,000) BHA (840) F12 pMADQUAT BHA BTA (0.16) 8.2 (250) (1,670) F13pMADQUAT SHA BTA (0.16) 8.2 (270) (840) F14 pMADQUAT SHA BTA (0.16) 8.2(270) (840) F15 pMADQUAT BHA BTA (0.16) 8.2 (270) (840)

Separate patterned coupon substrates (a square cut having 40 mm on eachside of a SKW 7-2 wafer from SKW Associates, Inc.) comprising 250 m TEOSfeatures with a 50% pattern density (approximately 20,000 Å thickfeatures) initially coated on patterned silicon substrates having astep-height of approximately 8,000 Å were polished for 60 sec on aPOLI-300 (G&P Tech. Inc.) having a 200 mm CMP platen using an IC1010™pad (Rohm and Haas Electronic Materials) at 20.68 kPa (3 psi) downforce, with 120 rpm and 110 rpm of platen speed and head speed,respectively. The total flow rate of the polishing composition was 200mL/min. The results are set forth in Table 3.

TABLE 3 Effect of Cationic Compound and pH on Polishing PerformanceAbrasive & AA TA Additive Re- Re- Polishing Compo- pH moval moval RatioComposition sitions (7:3) (POU) (Å) (Å) AA:TA 1A C1, F1 4.2 11,224 3,6713.06 (comparative) 1B C1, F3 4.2 8,643 1,460 5.92 (comparative) 1C C1,F4 7.6 8,984 1,279 7.02 (inventive) 1D C1, F5 7.6 7,412 725 10.22(inventive) 1E C1, F6 8.8 8,795 1,526 5.76 (inventive) 1F C1, F7 7.68,328 794 10.49 (inventive) 1G C1, F8 7.6 5,557 280 19.85 (inventive) 1HC2, F8 7.7 6,511 322 20.22 (inventive) 1I C1, F9 6.1 777 90 8.63(comparative) 1J C1, F10 7.6 9,045 717 12.62 (inventive) 1K C1, F11 7.66,739 229 29.43 (inventive) 1L C1, F12 7.6 7,776 589 13.20 (inventive)1M C2, F14 7.7 7,925 625 12.68 (inventive) 1N C1, F15 7.6 4,731 95 49.80(inventive)

As is apparent from the results set forth in Table 3, PolishingCompositions 1A and 1B, which comprise an abrasive formulation with aself-stopping agent (hydroxamic acid) at an acidic pH (pH 4.2),desirably exhibited a ratio of active area removal to trench arearemoval in a range of approximately 3 to 6. Thus, Polishing Compositions1A and 1B desirably are “self-stopping” compositions, which planarizepattern material while preserving trench material.

Polishing Composition 1I, which comprises both a self-stopping agent anda cationic compound, exhibited a ratio of active area removal to trencharea removal of approximately 8.6, and an active area removal of 777 Åat a pH of 6.1. Thus, Polishing Composition 1I also is a “self-stopping”composition, which planarizes pattern material while preserving trenchmaterial.

Polishing Compositions 1C-1H, and 1J-1N, which comprise both aself-stopping agent and a cationic compound, exhibited a ratio of activearea removal to trench area removal ranging from about 5.76:1 to about50:1 and an active area removal of about 4,700 Å to about 9,000 Å at apH of 7.6-8.8. Thus, Polishing Compositions 1C-1H, and 1J-1N are“self-stopping” compositions, which planarize pattern material whilepreserving trench material.

Example 2

This example demonstrates the effect of a self-stopping agent,optionally in combination with a cationic compound, on polishingperformance in polishing compositions comprising the same.

Pattern substrates were polished with three polishing compositions(i.e., Polishing Compositions 2A-2C). Polishing Compositions 2B and 2Cwere prepared using the Abrasive Compositions and Additive Formulationsdescribed in Example 1 (7:3 by volume). Composition 2A (comparative)contained only Abrasive Formulation C2.

Separate patterned substrates obtained from Silyb Inc. comprising TEOS(approximately 10,000 Å thick features) initially coated on patternedsilicon substrates with various widths and density having a step-heightof approximately 5,000 Å were polished for various times on an AP-300™(CTS Co., Ltd.) having a 300 mm CMP platen using an IC1010™ pad at 3 psidown force, with 93 rpm and 87 rpm of platen speed and head speed,respectively. The total flow rate of the polishing composition was 250mL/min.

TABLE 4 Description of Polishing Compositions 2A-2C Polishing Abrasive &Additive pH Polishing Composition Compositions (7:3) (POU) Time (s) 2AC2 4.2 35 (comparative) 2B C2:F2 4.2 35 and 45 (inventive) 2C C2:F12 7.730, 60, and 90 (inventive)

The remaining active thicknesses before and after polishing dependingupon pitch and pattern density as results of Example 2 are graphicallyrepresented in FIG. 2.

As is apparent from the results represented in FIG. 2, InventivePolishing Composition 2C, which contains abrasive, benzhydroxamic acid,and polyMADQUAT at a pH of 7.7 (POU), exhibited low pattern densitydependence as polishing time increased, and the stopping occurs withuniform topography over the substrate (Polishing Composition 2Cpolishing for 90 s) when compared to Polishing Compositions 2A and 2B.

Additional polishing performance data is set forth in Table 5 and FIG.2. Data in Table 5 depicts the remaining active thicknesses, whichcomprise 900 μm TEOS features (50% pattern density), over the wafer as afunction of polishing time.

TABLE 5 Remaining Silicon Oxide as a Function of Polishing TimePolishing Polishing AA Thickness (Å) TA Thickness (Å) Step Height (Å)Composition Time (s) Center Mid Edge Center Mid Edge Center Mid Edge NoPolishing 0 10394 10338 10224 10363 10307 10200 5045 5111 5074 2A 157181 7100 7320 9758 9642 9237 2544 2638 2986 (comparative) 35 3004 29103380 7728 7743 7785 378 255 513 2B 30 5574 5476 5865 9908 9883 9616 874983 1273 (comparative) 45 3297 3291 3774 8314 8434 8498 148 133 382 2C30 6222 6096 7303 9869 9855 10033 1416 1302 2009 (inventive) 60 45044464 5637 9369 9427 9759 327 412 738 90 4355 4333 4668 9209 9217 9292327 416 299

As is apparent from the results set forth in Table 5 and FIG. 2,Polishing Composition 2C initially exhibited a lower polishing rate onthe pattern material, but the rate drops uniformly over the wafer as thestep height decreases, as compared to comparative (PolishingCompositions 2A and 2B). This example further demonstrates the advantageof self-stopping polishing compositions formulated in a pH range ofabout 7.0 to about 8.5 at point-of-use with a self-stopping agent (e.g.,hydroxamic acid) and a cationic compound (e.g., pMADQUAT) with regard totopography variations over the substrate (pattern density dependence)and within wafer polishing rate variations (WIWNU) as compared to acontrol polishing composition.

Example 3

This example demonstrates the effect of self-stopping agents and pHranges of the present invention, optionally in combination with acationic compound, on polishing performance.

Pattern substrates and TEOS-coated silicon substrates were polished withthe fourteen polishing compositions described in Table 7 below (i.e.,Polishing Compositions 3A-3N). The polishing compositions were preparedby mixing the Abrasive Compositions (described in Table 1) and theAdditive Formulations described in Table 6, in a 7:3 ratio by volume.

Additive Formulations G1-G5 contained no cationic compound, whereasformulations G6-G14 contained a cationic compound (i.e. pMADQUAT orLuviquat Supreme). All formulations contained a self-stopping agent, andadditional components as set forth in Table 6.

TABLE 6 Additive Formulations Cationic Self-Stopping Additional CompoundAgent Components Formulation (ppm) (ppm) (ppm) pH G1 — Acetohydroxamic —4.0 acid (3333) G2 — Maltol (6667) — 4.0 G3 — Ethyl maltol (6667) — 4.0G4 — Deferiprone (1667) — 4.0 G5 — 2-Hydroxynicotinic — 4.0 acid (1667)G6 pMADQUAT Acetohydroxamic Acetic acid (1500) 5.0 (167) acid (1667) G7pMADQUAT Maltol (3333) Acetic acid (1500) 5.0 (100) G8 pMADQUATPotassium sorbate Acetic acid (1500) 4.0 (100) (1667) G9 pMADQUAT Tiglicacid (1667) Brij S20 (667) 4.0 (150) Acetic acid (1500) G10 pMADQUATCrotonic acid Brij S20 (667) 4.0 (150) (5000) G11 pMADQUAT 2-pentenoicacid Brij S20 (667) 4.0 (150) (1667) Acetic acid (1500) G12 pMADQUATValeric acid (3333) Acetic acid (1500) 4.0 (167) G13 pMADQUAT BHA (1670)Bis-Tris (4000) 7.0 (150) PEG8000 (1670) G14 Luviquat BHA (1670) BTA(1600) 8.2 Supreme TEA (4000) (333)

Patterned wafers were obtained from Silyb Inc., and comprised 900 m TEOSfeatures with a 50% pattern density (approximately 10,000 Å thickfeatures) initially coated on patterned silicon substrates having astep-height of approximately 5,000 Å. TEOS blanket wafers obtained fromWRS materials. The test wafers were polished using a MIRRA™ polishingtool (Applied Materials, Inc.) for 60 seconds and 90 seconds, for thepattern wafers and blanket wafers, respectively. A NexPlanar® E6088(Cabot Microelectronics Corporation) polishing pad was used on a 200 mmplaten, using 3 psi down force, and 93 rpm and 87 rpm for the platenspeed and head speed, respectively. The total slurry flow rate was 150mL/min. The results are set forth in Table 7.

TABLE 7 Effect of Additives and POU pH on Polishing PerformancePolishing Abrasive & Additive pH SH RR BW RR Ratio CompositionCompositions (7:3) (POU) (Å/min) (Å/min) SH:BW 3A C2, G1 4.0 3059 5066.04 (inventive) 3B C2, G2 3.9 3242 185 17.52 (inventive) 3C C2, G3 4.02940 213 13.80 (inventive) 3D C2, G4 4.0 2237 259 8.64 (inventive) 3EC2, G5 4.0 2285 543 4.21 (inventive) 3F C2, G6 4.8 2358 147 16.04(inventive) 3G C2, G7 4.8 2710 212 12.78 (inventive) 3H C2, G8 4.0 2550247 10.32 (inventive) 3I C2, G9 4.0 2691 525 5.13 (inventive) 3J C2, G104.0 2679 259 10.34 (inventive) 3K C2, G11 4.0 2727 353 7.72 (inventive)3L C2, G12 4.0 2598 330 7.87 (inventive) 3M C2, G13 6.1 2404 100 24.04(inventive) 3N C2, G14 7.7 2697 540 4.99 (inventive)

As is apparent from the results set forth in Table 7, all PolishingCompositions comprising an abrasive formulation with a self-stoppingagent exhibited high step-height removal rate on pattern, and low oxideremoval rate on blanket wafer. This indicates significant removal ratedrop occurs on pattern wafer as it is planarized. A ratio of step-heightremoval rate to oxide blanket removal rate was in a range ofapproximately 4 to 24, depending on the type of a self-stopping agent,in combination with POU pH and a cationic compound.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and “at least one” andsimilar referents in the context of describing the invention (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The use of the term “at least one”followed by a list of one or more items (for example, “at least one of Aand B”) is to be construed to mean one item selected from the listeditems (A or B) or any combination of two or more of the listed items (Aand B), unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

The invention claimed is:
 1. A chemical-mechanical polishing compositioncomprising: (a) a ceria abrasive, (b) less than about 1000 ppm ofpicolinic acid, (c) a self-stopping agent selected from a compound offormula (I):

wherein R is selected from the group consisting of hydrogen, alkyl,cycloalkyl, aryl, heterocyclic alkyl, and heterocyclic aryl, each ofwhich may be substituted or unsubstituted: (d) a cationic polymer,wherein the cationic polymer is selected from, 2-(dimethylamino)ethylmethacrylate, diallyldimethylammonium, poly(vinylimidazolium),poly(methacryloyloxyethyltnmethylammonium) halide,poly(diallyldimethylammonium) chloride, polyquaternium-2,Polyquatemium-11, Polyquatemium-16, Polyquatemium-46, Polyquatemium-44,Luviquat Supreme, Luviquat Hold, Luviquat UltraCare, Luviquat FC 370,Luviquat FC 550, Luviquat FC 552, Luviquat Excellence, and combinationsthereof, and (e) an aqueous carrier, wherein the polishing compositionhas a pH of about 6 to about
 9. 2. The polishing composition of claim 1,wherein the self-stopping agent is selected from hydroxamic acid,acetohydroxamic acid benzhydroxamic acid, salicylhydroxamic acid andcombinations thereof.
 3. The polishing composition of claim 1, whereinthe self-stopping agent is present in the polishing composition at aconcentration of about 1 wt. % or less.
 4. The polishing composition ofclaim 1, wherein the ceria abrasive is present in the polishingcomposition at a concentration of about 0.001 wt. % to about 5 wt. %. 5.The polishing composition of claim 1, wherein the ceria abrasive ispresent in the polishing composition at a concentration of about 0.05wt. % to about 2 wt. %.
 6. The polishing composition of claim 1, whereinthe median particle size of the ceria abrasive is about 40 nm to about100 nm.
 7. The polishing composition of claim 1, wherein the cationicpolymer is poly(methacryloyloxyethyltrimethylammonium) halide.
 8. Amethod of chemically-mechanically polishing a substrate comprising: (i)providing a substrate, wherein the substrate comprises a patterndielectric layer on a surface of the substrate, (ii) providing apolishing pad, (iii) providing the chemical-mechanical polishingcomposition comprising: (a) a ceria abrasive, (b) less than about 1000ppm of picolinic acid, (c) a self-stopping agent selected from acompound of formula (I):

wherein R is selected from the group consisting of hydrogen, alkyl,cycloalkyl, aryl, heterocyclic alkyl, and heterocyclic aryl, each ofwhich may be substituted or unsubstituted; (d) a cationic polymer,wherein the cationic polymer is selected from, 2-(dimethylamino)ethylmethacrylate, diallyldimethylammonium, poly(vinylimidazolium),poly(methacryloyloxyethyltrimethylammonium) halide,poly(diallyldimethylammonium) chloride, polyquatemium-2,Polyquaternium-11, Polyquaternium-16, Polyquaternium-46,Polyquatemium-44, Luviquat Supreme, Luviquat Hold, Luviquat UltraCare,Luviquat FC 370, Luviquat FC 550, Luviquat FC 552, Luviquat Excellence,and combinations thereof, and (e) an aqueous carrier, wherein thepolishing composition has a pH of about 6 to about 9, and (iv)contacting the substrate with the polishing pad and thechemical-mechanical polishing composition, and (v) moving the polishingpad and the chemical-mechanical polishing composition relative to thesubstrate to abrade at least a portion of the pattern dielectric layeron a surface of the substrate to polish the substrate.
 9. The method ofclaim 8, wherein the self-stopping agent is selected from hydroxamicacid, acetohydroxamic acid benzhydroxamic acid, salicylhydroxamic acidand combinations thereof.
 10. The method of claim 8, wherein theself-stopping agent is present in the polishing composition at aconcentration of about 1 wt. % or less.
 11. The method of claim 8,wherein the ceria abrasive is present in the polishing composition at aconcentration of about 0.001 wt. % to about 5 wt./.
 12. The method ofclaim 8, wherein the ceria abrasive is present in the polishingcomposition at a concentration of about 0.05 wt. % to about 2 wt. %. 13.The method of claim 8, wherein the median particle size of the ceriaabrasive is about 40 nm to about 100 nm.
 14. The method of claim 8,wherein the cationic polymer ispoly(methacryloyloxyethyltrimethylammonium) halide.